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29.1: Chordates - Biology


29.1: Chordates

Chordata

What is Chordata? Chordata is the phylum of the animal kingdom that includes a large number of animal species, including humans. Phylum Chordata animals include all animals that possess a notochord at least at one point in their lifetime.

A phylum is a taxonomy ranking that comes third after domain and kingdom in the hierarchy of the classification. The organisms belonging to a phylum share common characteristics that make them distinct from other organisms from another phylum. (Ref. 1) Chordata refers to a large phylum of animals that includes vertebrates as well as lancelets and sea squirts. Several well-known vertebrates, such as reptiles, fishes, mammals, and amphibians are included in the phylum Chordata.

What is a chordate?

The term “chordate” is used to refer to any animal belonging to the phylum Chordata. We can define chordate as follows: “The chordates are the class of animals that possess four anatomical features, namely (1) notochord, (2) dorsal nerve cord, (3) post-anal tail, and (4) pharyngeal slits, at least during some part of their development into maturity.”

Are all chordates vertebrates? How are chordates and vertebrates related?

All vertebrates are regarded as chordates. However, not all chordates are vertebrates.

Vertebrates, being a chordate, have a post-anal tail, a notochord, pharyngeal slits, and a dorsal hollow nerve cord. However, their notochord develops into a spine, which is a column of bony vertebrae separated by discs. Other general features of chordates that are present in vertebrates are as follows:

  • Bilateral symmetry
  • Segmented body
  • A fully developed coelom
  • A large anterior brain end with a hollow dorsal single nerve cord
  • The projection of tail far beyond the anus at any development stage
  • The existence of pharyngeal pouches
  • A ventral heart
  • A closed blood system
  • Ventral and dorsal blood vessels
  • The availability of a complete digestive system
  • The presence of cartilaginous and bony endoskeleton systems

Pandas, crows, sharks, salamanders, alligators, sea squirts, and many others are examples of chordates. So, in essence, to answer the question, amphibians, reptiles, and mammals comprise which group? — the answer is simply they belong to the phylum Chordata. And how about humans… Are humans chordates? Yes, humans are also chordates. At one point, the human embryo forms a notochord, which eventually becomes a vertebral column, particularly when the embryo is growing into a fetus. As already mentioned, any animal that has a notochord at any point in its life is considered a chordate.


Presentation Transcript

Biology - Chapter 29“Echinoderms and Invertebrate Chordates” Charles Page High School Stephen L. Cotton

Section 29-1Echinoderms • OBJECTIVES: • Relate the structure of echinoderms to essential life functions.

Section 29-1Echinoderms • OBJECTIVES: • Describe the characteristics of the classes of echinoderms.

Section 29-1Echinoderms • Phylum Echinodermata- starfish, sea urchins, sand dollars, etc. • echino- means spiny dermis means skin • these are spiny-skinned animals • Cambrian period 580 million yr.

Section 29-1Echinoderms • In addition to having spiny skin, they are characterized by: • 5 part radial symmetry • internal skeleton • water vascular system • suction-cuplike structures called “tube feet”

Section 29-1Echinoderms • The internal skeleton (or endoskeleton) is made up of hardened plates of calcium carbonate often bumpy or spiny • water vascular system consists of an internal network of fluid-filled canals connected to the external appendages called tube feet

Section 29-1Echinoderms • The water vascular system is essential for: • feeding respiration internal transport elimination of wastes and movement • Echinoderms have an internal skeleton like Chordates, and some similar development

Section 29-1Echinoderms • Thus, some biologists feel that among invertebrates, echinoderms are most closely related to humans! • Echinoderms are somewhat “ugly”- however, they are very well adapted to life in the sea have changed very little

Section 29-1Echinoderms • Adult echinoderms have a body plan with five parts organized symmetrically around a center • neither anterior nor posterior end no brain • but, they are two-sided • mouth side is the oral surface

Section 29-1Echinoderms • Side opposite the mouth is the aboral surface • they have a unique system of internal tubes called a water vascular system • opens to the outside through a sieve-like structure called the madreporite

Section 29-1Echinoderms • In starfish, the madreporite connects to a tube called the ring canal that forms a circle around the animal’s digestive system • Figure 29-3, page 639 • from the ring canal, five radial canals extend into each body segment

Section 29-1Echinoderms • Attached to each radial canal are hundreds of movable tube feet • this entire system acts like a series of living hydraulic pumps that can propel water in or out of the tube feet • can create a partial vacuum to hold on to what it is touching

Section 29-1Echinoderms • Feeding- • carnivores, such as starfish, use their tube feet to pry open the shells of bivalve mollusks • then flips the stomach out of it’s mouth, pours out enzymes, and digests it’s prey in its own shell then pulls the stomach back, leaving an empty shell

Section 29-1Echinoderms • Herbivores, such as sea urchins, scrape algae from rocks by using their 5-part jaw • Filter feeders, such as sea lilies, basket stars, and some brittle stars, use tube feet on flexible arms to capture plankton that float by on ocean currents

Section 29-1Echinoderms • Detritus feeders, such as sea cucumbers, move much like a bulldozer- taking in a mixture of sand and detritus • much like an earthworm, they digest the organic material and pass the sand grains out in their feces

Section 29-1Echinoderms • Respiration- in most species, the thin-walled tissue of the tube feet forms the main respiratory surface • in some species, small outgrowths called skin gills also function in gas exchange

Section 29-1Echinoderms • Internal transport- the functions of transporting oxygen, food, and wastes- which is normally done by a circulatory system, are shared by different systems in echinoderms • don’t really need a system for gases, because of gills and skin

Section 29-1Echinoderms • The distribution of nutrients is performed primarily by the digestive glands and the fluid within the body cavity • Excretion- in almost all echinoderms, solid wastes are released through the anus (on the aboral surface) as feces

Section 29-1Echinoderms • The nitrogen-containing cellular wastes are excreted primarily as ammonia • wastes seem to be excreted in many of the same places around the body in which gas exchange takes place- the tube feet and the skin gills

Section 29-1Echinoderms • Response- since they have no head, they have primitive nervous systems • they do have scattered sensory cells to detect food • starfish also have up to 200 light-sensitive cells clustered in eyespots at the tip of each arm

Section 29-1Echinoderms • However, they can do little more than tell whether it is light or dark • also may have statocysts for balance, telling them whether it is right side up • the spiny surface is not very good protection good in some such as the crown-of-thorns starfish

Section 29-1Echinoderms • Many predators have learned that if they turn these animals over, they can attack them through their unprotected underside • thus, many echinoderms hide during the day active at night when most predators sleep

Section 29-1Echinoderms • Movement- use tube feet and thin layers of muscle fibers attached to the plates of the endoskeleton to move • in sand dollars and sea urchins, the plates are fused together to form a rigid box that encloses the animal’s internal organs

Section 29-1Echinoderms • In sea cucumbers, the plates are reduced to tiny vestiges inside a soft, muscular body wall. The loss of the plates makes the body of sea cucumbers very flexible

Section 29-1Echinoderms • Reproduction- most echinoderms are either male or female, some are hermaphrodites • place the eggs and sperms in the water where fertilization takes place • the larvae have bilateral symmetry- very advanced

Section 29-1Echinoderms • When the larvae mature and metamorphose into adults, they have radial symmetry • many starfish have incredible powers of regeneration • each piece can grow into a new animal as long as it contains a portion of the central part

Section 29-1Echinoderms • Echinoderm Classes- 5 classes, although exact names not given • almost 6,000 species found in almost every ocean (salt water) in the world • no echinoderms have ever entered fresh water, and they cannot survive for long on land

Section 29-1Echinoderms • 1. Starfish- this class contains the common starfish, which are also known as sea stars • some have more than 5 arms • Figure 29-7, page 642 • carnivorous, preying upon the bivalves they encounter

Section 29-1Echinoderms • 2. Brittle Stars- live in tropical seas, especially on coral reefs • look like common starfish, but longer more flexible arms- thus able to move much more rapid • protection by shedding one or more arms when attacked are filter and detritus feeders

Section 29-1Echinoderms • 3. Sea Urchins and Sand Dollars- includes disk-shaped sand dollars, oval heart urchins, and round sea urchins Fig. 29-8, p. 643 • are grazers that eat large quantities of algae may burrow into the sand or mud may protect by long sharp spines

Section 29-1Echinoderms • 4. Sea Cucumbers- look like warty moving pickles, with a mouth at one end and an anus at the other • Figure 29-9, page 644 top • most are detritus feeders • some produce a sticky material to “glue” a predator helpless

Section 29-1Echinoderms • 5. Sea Lilies and Feather Stars- filter feeders, have 50 or more long feathery arms • the most ancient class of echinoderms not common today, but once were widely distributed • sea lilies: sessile animals-p.644

Section 29-1Echinoderms • How Do Echinoderms Fit Into the World? • Starfish are important carnivores, controlling other animal populations a rise or fall in numbers affects other populations

Section 29-1Echinoderms • For example, several years ago the coral-eating crown-of-thorns starfish suddenly appeared in great numbers in the Pacific Ocean • within a short period of time, they caused extensive damage to many coral reefs

Section 29-1Echinoderms • In many coastal areas, sea urchins are important because they control distribution of algae • in various parts of the world, sea urchin eggs and sea cucumbers are considered delicacies by some people

Section 29-1Echinoderms • Several chemicals from starfish and sea cucumbers are currently being studied as potential anti-cancer and anti-viral drugs • sea urchins have been helpful in embryolgy study, since they produce large eggs fertilize externally develop in sea water

Section 29-2Invertebrate Chordates • OBJECTIVES: • Name and discuss the three distinguishing characteristics of chordates.

Section 29-2Invertebrate Chordates • OBJECTIVES: • Describe the two subphyla of invertebrate chordates.

Section 29-2Invertebrate Chordates • The phylum Chordata, to which fishes, frogs, birds, snakes, dogs, cows, and humans belong, will be in future chapters • most chordates are vertebrates, which means they have backbones, and are placed in the subphylum Vertebrata

Section 29-2Invertebrate Chordates • But, there are also invertebrate chordates- these are divided into two subphyla: • 1. the tunicates • 2. the lancelets • due to similar structures, the chordate vertebrates and invertebrates may have evolved from a common ancestor

Section 29-2Invertebrate Chordates • Chordates are animals that are characterized by a notochord, a hollow dorsal nerve cord, and pharyngeal (throat) slits • some chordates posses these characteristics as adults others as only embryos but all have them at some stage of life

Section 29-2Invertebrate Chordates • 1. Notochord- a long, flexible supporting rod that runs through at least part of the body, usually along the dorsal surface just beneath the nerve cord • most chordates only have this during the early part of embryonic life

Section 29-2Invertebrate Chordates • Vertebrates will replace the notochord quickly with the backbone • 2. The second chordate characteristic- the hollow dorsal nerve cord- runs along the dorsal surface just above the notochord

Section 29-2Invertebrate Chordates • In most chordates, the front end of this nerve cord develops into a large brain • nerves leave this cord at regular intervals along the length of the animal, and connect it’s internal organs, muscles, and sense organs

Section 29-2Invertebrate Chordates • 3. The third chordate characteristic- the pharyngeal slits- are paired structures in the pharyngeal (or throat) region of the body • in aquatic chordates such as lancelets and fishes, the pharyngeal slits are gill slits that connect with the outside

Section 29-2Invertebrate Chordates • In terrestrial chordates that use lungs for respiration, pharyngeal slits are present for only a brief time during the development of the embryo • they soon close up as the embryo develops- page 283

Section 29-2Invertebrate Chordates • In humans, pouches form in the pharyngeal region, but never open up to form slits • thus, some scientists consider the pharyngeal pouches, not slits, as the “true” chordate characteristic

Section 29-2Invertebrate Chordates • Tunicates- small marine chordates that eat plankton they filter from the water • name from a special body covering called the tunic • only the tadpole-shaped larvae have the notochord and dorsal nerve cord

Section 29-2Invertebrate Chordates • Examples of tunicates are the sea squirts Figure 29-11, page 646 • adults are sessile, living as colonies attached to a solid surface larvae are free swimming

Section 29-2Invertebrate Chordates • Lancelets- small fishlike creatures live in sandy bottoms of shallow tropical oceans • unlike tunicates, the adult lancelets have a definite head a mouth that opens into a long pharyngeal region with up to 100 pairs of gills


Origins

The majority of animals more complex than jellyfish and other Cnidarians are split into two groups, the protostomes and deuterostomes, and chordates are deuterostomes. ⎞] It seems very likely that Template:Ma/1 million years old Kimberella was a member of the protostomes. ⎟] ⎠] If so, this means that the protostome and deuterostome lineages must have split some time before Kimberella appeared - at least Template:Ma/1 million years ago , and hence well before the start of the Cambrian Template:Ma/1 million years ago . ⎞] The Ediacaran fossil Ernettia, from about 549 to𧌟 million years ago , may represent a deuterostome animal. ⎡]

Haikouichthys, from about Template:Ma/1 million years ago in China, may be the earliest known fish. ⎢]

Fossils of one major deuterostome group, the echinoderms (whose modern members include starfish, sea urchins and crinoids) are quite common from the start of the Cambrian, Template:Ma/1 million years ago . ⎣] The Mid Cambrian fossil Rhabdotubus johanssoni has been interpreted as a pterobranch hemichordate. ⎤] Opinions differ about whether the Chengjiang fauna fossil Yunnanozoon, from the earlier Cambrian, was a hemichordate or chordate. ⎥] ⎦] Another Chenjiang fossil, Haikouella lanceolata, also from the Chengjiang fauna, is interpreted as a chordate and possibly a craniate, as it shows signs of a heart, arteries, gill filaments, a tail, a neural chord with a brain at the front end, and possibly eyes - although it also had short tentacles round its mouth. ⎦] Haikouichthys and Myllokunmingia, also from the Chenjiang fauna, are regarded as fish. ⎢] ⎧] Pikaia, discovered much earlier but from the Mid Cambrian Burgess Shale, is also regarded as a primitive chordate. ⎨] On the other hand fossils of early chordates are very rare, since non-vertebrate chordates have no bones or teeth, and none have been reported for the rest of the Cambrian.

The evolutionary relationships between the chordate groups and between chordates as a whole and their closest deuterostome relatives have been debated since 1890. Studies based on anatomical, embryological, and paleontological data have produced different "family trees". Some closely linked chordates and hemichordates, but that idea is now rejected. Α] Combining such analyses with data from a small set of ribosome RNA genes eliminated some older ideas, but open the possibility that tunicates (urochordates) are "basal deuterostomes", in other words surviving members of the group from which echinoderms, hemichordates and chordates evolved. ⎪] Most researchers agree that, within the chordates, craniates are most closely related to cephalochordates, but there also reasons for regarding tunicates (urochordates) as craniates' closest relatives. Α] ⎫] One other phylum, Xenoturbellida, appears to be basal within the deuterostomes, in other words closer to the original deuterostomes than to the chordates, echinoderms and hemichordates. ⎩]

Since chordates have left a poor fossil record, attempts have been made to calculate the key dates in their evolution by molecular phylogenetics techniques, in other words by analysing biochemical differences, mainly in RNA. One such study suggested that deuterostomes arose before Template:Ma/1 million years ago and the earliest chordates around Template:Ma/1 million years ago . ⎫] However molecular estimates of dates often disagree with each other and with the fossil record, ⎫] and their assumption that the molecular clock runs at a known constant rate has been challenged. ⎬] ⎭]


Start Quiz: Biology 29 Vertebrates MCQ Quiz OpenStax

This NASA image is a composite of several satellite-based views of Earth. To make the whole-Earth image, NASA scientists combine observations of different parts of the planet. (credit: NASA/GSFC/NOAA/USGS)

Viewed from space, Earth offers no clues about the diversity of life forms that reside there. The first forms of life on Earth are thought to have been microorganisms that existed for billions of years in the ocean before plants and animals appeared. The mammals, birds, and flowers so familiar to us are all relatively recent, originating 130 to 200 million years ago. Humans have inhabited this planet for only the last 2.5 million years, and only in the last 200,000 years have humans started looking like we do today.

Chapter 29: Vertebrates MCQ Multiple Choices Questions Quiz Test Bank

29.7 The Evolution of Primates

Name: Biology 29 Vertebrates MCQ
Download URL: Download MCQ Quiz PDF eBook
Book Size: 14 Pages
Copyright Date: 2015
Language: English US
Categories: Educational Materials

Question: Members of Chondrichthyes differ from members of Osteichthyes by having a ________.

Question: During the Mesozoic period, diapsids diverged into_______.

lepidosaurs and archosaurs

Testudines and Sphenodontia

Question: Which of the following feather types helps to reduce drag produced by wind resistance during flight?

Question: A bird or feathered dinosaur is ________.

Question: Squamata includes_______.

crocodiles and alligators

Question: Which of the following is not contained in phylum Chordata?

Question: Eccrine glands produce ________.

Question: Members of Chondrichthyes are thought to be descended from fishes that had ________.

Question: Which of the following is not true of Acanthostega?

Question: Which group of Vertebrates is most closely related to vertebrates?


Malith Perera Biology

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Phylum Mollusca Majority are marine. Some inhabit freshwater and land. Some are bilateral symmetrical and few are asymmetrical. They are soft.

Phylum Annelida Characteristic features of each examples are not necessary e.g. Earthworms, Leeches and regworms. They can be marine, freshwater or.

Phylum Nematoda Most of them are free living in marine, few are fresh water and damp soil environments and parasitic in plants and animals. They.


Saturday, May 30, 2015

The Non-Jawed Chordate Lineages of the World Series Part II

A typical lancelet Branchiostoma. Drawing by Giovanni Maki.
If you recall last time I have briefly talked about the kinds of animals that make up Phylum Chordata, what unites us all in this extraordinary lineage, and some of the conflicting phylogenetic work on the interrelationships among the chordate subphyla. All of this can be read here. Today in Part II of the series will be a post on the lancelets of Subphylum Cephalochordata.

  • Branchiostomidae which only contains the genus Branchiostoma
  • Asymmetronidae which includes the genera Epigonichthys and Asymmetron
Pikaia fossil. Photo by Jstuby.
The fossil record of lancelets is very scarce due to their small, translucent bodies. Needless to say there are at least three fossil genera, which unsurprisingly look like modern lancelets. Indeed lancelets as a whole have virtually unchanged for 530 million years. Although I should point out there is a whole cast of fossil chordates and/or stem-chordates that resemble lancelets such as the relatively famous Pikaia gracilens. These primitive chordates and lancelets probably were similar in anatomy, although it should be noted that these animals can not be placed firmly in any of the three modern subphyla (Lacalli, 2012). Despite this, this makes lancelets prized as lab animals or modeled organisms in college classrooms and labs when discussing about the earliest chordates. I can certainly understand the attraction, although I think we need to be mindful that lancelets could be slightly more derived than an animal like Pikaia. What is more, the probable behavior and some aspects of their biology in lancelets and early chordates was probably a bit different (Morris & Caron, 2012). Needless to say, lancelets still serve a purpose in understanding the evolution of chordate anatomy.

As mention earlier the overall appearance of these chordates is somewhat not unlike that of lamprey larva. However lancelets lack a cranium case around the head region, thus they lack a distinctive head shape. The brain is very simple and lacks most of the sensory organs, although they have a photoreceptive frontal organ which is ancestral to the vertebrate eye. The pharynx and the gill slits act as filter-feeding apparatus, which the movement of water containing food particles goes through via cilia action. The cilia are dozens of tentacle-like structures near the opening or the ridges of the mouth known as the "wheel of organ". Another series of tentacle-like organs are the oral cirri which also partakes in the action.

A - Lamprey larva B - Lancelet adult.

Being a invertebrate it has no true backbone. To protect the notochord lancelets have stiffen cells that surround the region. The notochord extends from the tip of the snout to the end of the tail. In addition to giving the animal support and structure, it also helps lancelets to burrow themselves in the sand in coastal waters. To move around lancelets swim in side-to-side action with the help of the myomeres. The tail is fishlike in appearance and can swim surprisingly well. They do not have an recognizable fins except for a dorsal fin.

But what is peculiar about the overall anatomy of lancelets is that most of the organ systems are alternated on either sides of the animal as opposed to being set in a series of successions on either side seen in vertebrates. Not surprisingly, their organ systems in particular their circulatory system and digestive system is simple in comparison to our own For example the lancelets do not have a recognizable true heart nor neural control for pumping blood the circulatory system is more large and open and no red blood cells. There is no muscular stomach, liver and pancreas (though midgut cecum might be homologous to the last two organs Pough et. al, 2005).

Lancelets have multiple gonads that produce large quantities of sperm and eggs (noticed the circular organs in the image above in this post.), which leads us to our final segment for the lancelets.

Life History

Typical feeding fashion. Photo by Colin Gray.

All species of lancelets have more or less the same life story. All species reproduce sexually and spawn sperm and eggs which simultaneously fertilized in the water. Once the young hatch they buried themselves in the sand where they mature. Most of their adult too is buried in the sand, with their heads sticking out as they are filtering out the food from the environment. However lancelets are forever capable of free-swimming animals and they hardly changed their physical appearance. It would probably surprise some people to know that lancelets are considered to be a food source in Asian countries, often used as animal feed for domesticated animals.

What's Next?
The next group will be the tunicates. As they are the most diverse and numerous of the groups that will be cover in this series, there might be a two-part articles concerning them. In the first post of the two articles will be in similar fashion to this article, but in the second post will briefly go over the life histories of the three classes of the tunicates.

  • Hildebrand, M. & Goslow, G. (2001). Analysis of Vertebrate Structure. John Wiley & Sons, 24-25.
  • Lacalli, T. (2012). The Middle Cambrian fossil Pikaia and the evolution of chordate swimming. EvoDevo, 3(1), 1-6.
  • Li, G., Yang, X., Shu, Z., Chen, X., & Wang, Y. (2012). Consecutive spawnings of Chinese amphioxus, Branchiostoma belcheri, in captivity. PloS one, 7(12), e50838.
  • Morris, S. C., & Caron, J. B. (2012). Pikaia gracilens Walcott, a stem‐group chordate from the Middle Cambrian of British Columbia. Biological Reviews, 87(2), 480-512.
  • Pough, F. H., Janis, C. M., & Heiser, J. B. (2005). Vertebrate Life. Pearson/Prentice Hall, 23 27.

Deep RNA sequencing reveals the smallest known mitochondrial micro exon in animals: The placozoan cox1 single base pair exon

The phylum Placozoa holds a key position for our understanding of the evolution of mitochondrial genomes in Metazoa. Placozoans possess large mitochondrial genomes which harbor several remarkable characteristics such as a fragmented cox1 gene and trans-splicing cox1 introns. A previous study also suggested the existence of cox1 mRNA editing in Trichoplax adhaerens, yet the only formally described species in the phylum Placozoa. We have analyzed RNA-seq data of the undescribed sister species, Placozoa sp. H2 ("Panama" clone), with special focus on the mitochondrial mRNA. While we did not find support for a previously postulated cox1 mRNA editing mechanism, we surprisingly found two independent transcripts representing intermediate cox1 mRNA splicing stages. Both transcripts consist of partial cox1 exon as well as overlapping intron fragments. The data suggest that the cox1 gene harbors a single base pair (cytosine) micro exon. Furthermore, conserved group I intron structures flank this unique micro exon also in other placozoans. We discuss the evolutionary origin of this micro exon in the context of a self-splicing intron gain in the cox1 gene of the last common ancestor of extant placozoans.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1. Placozoan cox1 “mRNA editing” scenario.

Fig 1. Placozoan cox1 “mRNA editing” scenario.

The shown scenario is based on Trichoplax adhaerens…

Fig 2. Schematic cox1 transcript mapping.

Fig 2. Schematic cox1 transcript mapping.

Shown are transcripts W, X and Y (assembled from…

Fig 3. Mapping of RNA-seq reads on…

Fig 3. Mapping of RNA-seq reads on the partial Placozoa sp. H2 "Panama" cox1 gene…

Fig 4. Placozoan cox1 “micro exon” scenario.

Fig 4. Placozoan cox1 “micro exon” scenario.

The scenario is based on Placozoa sp. H2…

Fig 5. Conserved splicing sites and intron…

Fig 5. Conserved splicing sites and intron motifs in the placozoan cox1 gene.

Fig 6. The evolutionary origin of the…

Fig 6. The evolutionary origin of the cox1 micro exon in Placozoa.


Clarias gariepinus

Clarias gariepinus has all the qualities of an aggressive and successful invasive species. Its high fecundity, flexible phenotype, rapid growth, wide habitat preferences, tolerance to extreme water conditions and the ability to subsist on.

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Pictures

TitleAdult
CaptionClarias gariepinus (African sawtooth catfish) adult, on a ford after jumping upsteam. Mlondozi Ford, S129 Road North of Lower Sabie, Kruger NP, South Africa. January, 2014.
Copyright©Bernard Dupont-2014/via wikipedia - CC BY-SA 2.0
TitleAdult
CaptionClarias gariepinus (African sawtooth catfish) adult, captive speimen. Bogor, West Java, Indonesia. May, 2008.
Copyright©Wibowo A. Djatmiko-2008/Bogor, West Java, Indonesia/via wikipedia - CC BY-SA 3.0
TitleAdult
CaptionClarias gariepinus (African sawtooth catfish) adult, anterior section, captive speimen. Bogor, West Java, Indonesia. May, 2008.
Copyright©Wibowo A. Djatmiko-2008/Bogor, West Java, Indonesia/via wikipedia - CC BY-SA 3.0
TitleJuvenile
CaptionClarias gariepinus juvenile, showing distinct mottled body coloration.
Copyright©Wing-Keong Ng

Identity

Preferred Scientific Name

Other Scientific Names

  • Clarias capensis Valenciennes, 1840
  • Clarias depressus Myers, 1925
  • Clarias guentheri Pfeffer, 1896
  • Clarias lazera Valenciennes, 1840
  • Clarias longiceps Boulenger, 1899
  • Clarias macracanthus Günther, 1864
  • Clarias malaris Nichols & Griscom, 1917
  • Clarias micropthalmus Pfeffer, 1896
  • Clarias moorii Boulenger, 1901
  • Clarias mossambicus Peters, 1852
  • Clarias muelleri Pietschmann, 1939
  • Clarias notozygurus Lönnberg & Rendahl, 1922
  • Clarias orontis Günther, 1864
  • Clarias robecchii Vinciguerra, 1893
  • Clarias smithii Günther, 1896
  • Clarias syriacus Valenciennes, 1840
  • Clarias tsanensis Boulenger, 1902
  • Clarias vinciguerrae Boulenger, 1902
  • Clarias xenodon Günther, 1864
  • Silurus gariepinus Burchell, 1822

International Common Names

  • English: African catfish African magur catfish, African mudfish North African catfish sharptooth catfish
  • Spanish: pez gato
  • French: poisson-chat nord-Africain
  • Russian: yuzhnoafrikanskaya zubatka
  • Arabic: abu shanab balbout garmut karmut

Local Common Names

  • Angola: mburi
  • Cambodia: trey andaing Afrik
  • Ethiopia: ambaazaa
  • Germany: aalbuschelwels Afrikanischer raubwels Afrikanischer wels kiemensackwels
  • Greece: klarias
  • Indonesia: keli Afrika
  • Israel: sfamnun matzui
  • Japan: namazu
  • Kenya: mumi
  • Malawi: mlamba
  • Malaysia: keli Afrika
  • Mozambique: nsomba
  • Namibia: skerptandbaber
  • Netherlands: Afrikaanse meerval
  • Nigeria: arira aro ejengi imunu kemudu tarwada
  • Poland: stawada
  • Senegal: baleewu bambara talage toucouleurs yess
  • Sierra Leone: harlei thamba t-nima
  • South Africa: skerptandbaber
  • Sudan: attek cik cogo kor pet cick pet der tukpe
  • Tanzania: kambale mlamba mumi
  • Uganda: eyisombi
  • Zambia: mulonge muta

Summary of Invasiveness

Clarias gariepinus has all the qualities of an aggressive and successful invasive species. Its high fecundity, flexible phenotype, rapid growth, wide habitat preferences, tolerance to extreme water conditions and the ability to subsist on a wide variety of prey can devastate indigenous fish and aquatic invertebrate populations (Bruton, 1986). It is because of these characteristics that countries such as India have imposed a ban on the introduction and culture of C. gariepinus (Dhawan and Kaur, 2001). Nevertheless, the effects of the illegal and indiscriminate introduction of this fish into India, as in other countries, have brought about potential ecological problems such as the loss of biodiversity in natural inland waters (Singh, 2000). Genetic introgression of native wild clariid catfish by escapees of hybrid catfish (C. gariepinus x C. macrocephalus) from fish farms have been reported in Thailand (Senanan et al., 2004).

The introduction of C. gariepinus into Asia has resulted in the rapid expansion of the hybrid catfish culture when the exotic male C. gariepinus is hybridized with local female clariid species. The resultant hybrid with high growth rates and disease resistance (from paternal genes), and high flesh quality and taste (from maternal genes), is very popular with fish farmers and has almost completely replaced the native clariid catfish aquaculture in countries such as Thailand (Poompuang and Na-Nakorn, 2004). It has given a great boost to the aquaculture of clariid catfishes in many Asian countries and positively impacted the livelihoods of many catfish farmers.

Taxonomic Tree

  • Domain: Eukaryota
  • Kingdom: Metazoa
  • Phylum: Chordata
  • Subphylum: Vertebrata
  • Class: Actinopterygii
  • Order: Siluriformes
  • Family: Clariidae
  • Genus: Clarias
  • Species: Clarias gariepinus

Description

Clarias gariepinus are readily recognized by their cylindrical body with scaleless skin, flattened bony head, small eyes, elongated spineless dorsal fin and four pairs of barbels around a broad mouth. The upper surface of the head is coarsely granulated in adult fishes but smooth in young fish (Van Oijen, 1995). The anal, caudal and dorsal fins are not united. The males can be easily recognized by a distinct sexual papilla located immediately behind the anal opening. This sexual papilla is not present in female fish.

The body is greyish-black with the underside of the head and body a creamy-white colour (Van Oijen, 1995), with a distinct black longitudinal band on each side of the ventral surface of the head (which is absent in young fish of less than 9 cm long). Larger fish (more than 9 cm) are mottled with an overall grey-khaki colour. Skin coloration is known to change slightly according to substrate and light intensity in culture systems.

Distribution

Clarias gariepinus is indigenous to the inland waters of much of Africa and they are also endemic in Asia Minor in countries such as Israel, Syria and the south of Turkey. C. gariepinus has been widely introduced to other parts of the world including the Netherlands, Hungary, much of South-East Asia and East Asia. This species can be cultivated in areas with a tropical climate, areas with access to geothermal waters or with the use of heated recirculating water systems. It is a hardy fish that can be densely stocked in low oxygen waters making it ideal for culture in areas with a limited water supply. Its air-breathing ability, high fecundity, fast growth rate, resistance to disease and high feed conversion efficiency makes C. gariepinus the freshwater species with the widest latitudinal range in the world.

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Africa

Europe

Introductions

Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Bangladesh Thailand 1989 Aquaculture (pathway cause)Unknown Yes No Welcomme (1988)
Cambodia 1982 Unknown No No Csavas (1995) Csavas (1995)
Cameroon 1972 Unknown No No Welcomme (1988)
China Central African Republic 1981 Aquaculture (pathway cause)Private sector Yes No Welcomme (1988)
Congo 1973 Unknown No No FAO (1997)
Congo Democratic Republic 1972 Unknown No No Welcomme (1988)
Côte d'Ivoire 1972 Unknown No No Welcomme (1988)
Gabon Unknown No No FAO (1997)
India Unknown No No Shaji et al. (2000)
Indonesia Netherlands 1985 Aquaculture (pathway cause) Research (pathway cause)Government Yes No Csavas (1995) Csavas (1995)
Laos 1980 Unknown No No Kottelat (2001) Kottelat (2001a) Kottelat et al. (2001a)
Malaysia Thailand 1986-1989 Aquaculture (pathway cause)Private sector Yes No Csavas (1995) Csavas (1995)
Mauritius 1989 Unknown No No FAO (1997)
Myanmar 1990 Unknown No No FAO (1997)
Netherlands Côte d'Ivoire Aquaculture (pathway cause) Research (pathway cause)Government Individual No No Welcomme (1988)
Philippines Thailand 1985 Aquaculture (pathway cause)Private sector Yes No Juliano and et al. (1989) Juliano et al. (1989)
Thailand 1987 Unknown No No FAO (1997)
Vietnam Central African Republic 1974 Aquaculture (pathway cause)Private sector Yes No FAO (1997)

Habitat List

Natural Food Sources

Food SourceFood Source DatasheetLife StageContribution to Total Food Intake (%)Details
aquatic insects/insect larvae Adult Broodstock
crustacea Adult Fry
molluscs Adult Broodstock
plant debris Adult Fry
terrestrial insects/insect larvae Adult Broodstock
zooplankton Fry Larval

Climate

ClimateStatusDescriptionRemark
A - Tropical/Megathermal climate Preferred Average temp. of coolest month > 18°C, > 1500mm precipitation annually

Water Tolerances

ParameterMinimum ValueMaximum ValueTypical ValueStatusLife StageNotes
Cadmium (mg/l) 10.85 Harmful Adult
Copper (mg/l) 1.29 1.38 Harmful Adult
Phosphate (mg/l) 0.5 Optimum Egg
Phosphate (mg/l) 0.5 Optimum Larval
Phosphate (mg/l) 0.5 Optimum Fry
Salinity (part per thousand) >6 Harmful Broodstock
Salinity (part per thousand) 7.5 Harmful Larval
Salinity (part per thousand) 0 2 Optimum Broodstock
Salinity (part per thousand) 0 5 Optimum Larval
Spawning temperature (ºC temperature) >22 Optimum Broodstock
Spawning temperature (ºC temperature) >30 Harmful Broodstock
Water temperature (ºC temperature) 22 Optimum Broodstock
Water temperature (ºC temperature) >30 Harmful Broodstock
Water temperature (ºC temperature) 10 Harmful Larval
Water temperature (ºC temperature) 20 35 Optimum Egg
Water temperature (ºC temperature) 25 33 Optimum Larval

Natural enemies

Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Crocodylus niloticus Predator Adult Broodstock Whitfield and Blaber (1979)
Cybister Predator Larval Adeyemo et al. (1997)
Eretes Predator Larval Adeyemo et al. (1997)
Notonecta Predator Larval Adeyemo et al. (1997)

Impact Summary

CategoryImpact
Biodiversity (generally) Negative
Environment (generally) Negative
Fisheries / aquaculture Positive
Native fauna Negative

Uses List

Human food and beverage

  • Cured meat
  • Fresh meat
  • Frozen meat
  • Live product for human consumption
  • Whole

References

Bailey RG, 1994. Guide to the fishes of the River Nile in the Republic of the Sudan. J. Nat. Hist., 28:937-970

Bell-Cross G, Minshull JL, 1988. The fishes of Zimbabwe. National Museums and Monuments of Zimbabwe, Harare. 294 pp

Beveridge MCM, Haylor GS, 1998. Warm-water farmed species. In: Black KD, Pickering AD, eds. Biology of Farmed Fish. Sheffield Academic Press, 393-394

Britz PJ, Pienaar AG, 1992. Laboratory experiments on the effect of light and cover on the behaviour and growth of African catfish, Clarias gariepinus (Pisces: Clariidae). Journal of Zoology, 227:43-62

Bruton MN, 1979. Breeding biology and early development of Clarias gariepinus (Pisces: Clariidae) in Lake Sibaya, South Africa, with a review of breeding in species of the subgenus Clarias. Transactions of the Zoological Society of London, 35(1):1-46

Bruton MN, 1979. The food and feeding behaviour of C. gariepinus (Pisces: Clariidae) in Lake Sibaya, S. Africa, with emphasis on its role as a predator of cichlids. Transactions of the Zoological Society of London, 35:47-114

Bruton MN, 1986. The life history styles of invasive fishes in southern Africa. In: Macdonald IAW, Kruger FJ, Ferrar AA, eds. The Ecology and Management of Biological Invasions in southern Africa, Oxford University Press, Cape Town, 201-209

Csavas I, 1995. Status and perspectives of culturing catfishes in East and South-East Asia. Presented at the International Workshop on the Biological Bases for Aquaculture of Siluriformes, May, Montpellier, France

De Graaf G, Janssen H, 1996. Artificial reproduction and pond rearing of the African catfish Clarias gariepinus in sub-Saharan Africa. A handbook. FAO Fisheries Technical Paper no. 362: FAO, Rome, 73 pp

Degani G, Ben-Zvi Y, Levanon D, 1989. The effect of different protein levels and temperatures on feed utilization, growth and body composition of Clarias gariepinus (Burchell, 1822). Aquaculture, 76:293-301

Dhawan A, Kaur K, 2001. Clarias gariepinus in Punjab waters. Fishing Chimes, 21:56

Eding EH, Schneider O, Ouwerkerk ENJ, Klapwijk A, Verreth JAJ, Aarnink AJA, 2002. The effect of fish biomass and denitrification on the energy balance in African catfish farms. In: Proceedings of the Third International Conference on Recirculating Aquaculture, Virginia, USA, 20-23 July, 2000. US Department of Agriculture, Virginia Polytechnic Institute and State University, USA

Efiuvwevwere BJO, Ajiboye MO, 1996. Control of microbiological quality and shelf-life of catfish (Clarias gariepinus) by chemical preservatives and smoking. Journal of Applied Bacteriology, 80:465-470

Eschmeyer WN, 2003. Catalog of fishes. Updated database version of March 2003. Catalog databases as made available to FishBase in March 2003

FAO, 1997. FAO Database on Introduced Aquatic Species. FAO, Rome, Italy: Food and Agricultural Organization of the United Nations

FAO, 2002. Aquaculture production: values 1984-2001. FAO Yearbook. Fishery statistics. Aquaculture production 2001 vol. 92/2. FAO, Rome

Hecht T, Oellermann L, Verheust L, 1996. Perspectives on clariid catfish culture in Africa. In: Legendre M, Proteau JP, eds. The Biology and Culture of Catfishes, Aquatic Living Resources, 197-206

Hossain MA, Begum S, Islam MN, Shah AKMA, 1998. Studies on the optimum protein to energy ratio of African catfish (Clarias gariepinus Burchell). Bangladesh Journal of Fisheries Research, 2:47-54

Jubb RA, 1967. Freshwater Fishes of southern Africa. AA Balkema, Cape Town/Amsterdam, 248 pp

Juliano RO, Guerrero R III, Ronquillo I, 1989. The introduction of exotic aquatic species in the Philippines. In: De Silva SS, ed. Proceedings of the Workshop on Introduction of Exotic Aquatic Organisms in Asia: The Asian Fisheries Society, 83-90

Klinkhardt M, Tesche M, Greven H, 1995. Database of fish chromosomes. Westarp Wissenschaften, 179 pp

Kottelat M, 2001. Fishes of Laos. Colombo, Sri Lanka: WHT Publications Ltd., 198 pp

Krupp F, Schneider W, 1989. The fishes of the Jordan River drainage basin and Azraq Oasis. In: Fauna of Saudi Arabia, volume 10, 347-416 pp

Ng WK, 2002. The nutrient requirements of clariid catfishes. Aqua Feed International, 5:14-18

Nwadukwe FO, 1995. Analysis of production, early growth and survival of Clarias gariepinus (Burchell), Heterobranchus longifilis (Val.) (Pisces: Clariidae) and their F1 hybrids in ponds. Netherlands Journal of Aquatic Ecology, 29:177-182

Paugy D, Traoré K, Diouf PS, 1994. Faune ichtyologique des eaux douces d’Afrique de l’Ouest. In: Teugels GG, Guégan JF, Albaret JJ, eds. Biological diversity of African fresh- and brackish water fishes. Geographical overviews presented at the PARADI Symposium, Senegal, 15-20 November 1993. Ann. Mus. R. Afr. Centr., Sci. Zool., 275:35-66

Prinsloo JF, Schoonbee HJ, 1992. Evaluation of the poly- and monoculture production of the common carp Cyprinus carpio L. and the sharptooth catfish Clarias gariepinus (Burchell) in final effluent oxidation pond water of a sewage purification system. Water SA, 18:7-12

Proteau JP, Hilge V, Linhart O, 1996. Present state and prospects of the aquaculture of catfishes (Siluroidei) in Europe. In: Legendre M, Proteau JP, eds. The Biology and Culture of Catfishes, Aquatic Living Resources, 229-235

Rahman MM, Varga I, Choudhury SN, 1992. Manual on African magur (Clarias gariepinus) culture in Bangladesh. FAO/UNDP Project on Institution Strengthening in the Fisheries Sector, Dhaka, Bangladesh. FAO/UNDP, Dhaka, Bangladesh, 43 pp

Schoonbee HJ, Hecht T, Polling L, Saayman JE, 1980. Induced spawning of hatchery procedures with the sharp toothed catfish, C. gariepinus. South Africa Journal of Science, 76:364-367

Senanan W, Kapuscinski AR, Na-Nakorn U, Miller LM, 2004. Genetic impacts of hybrid catfish farming (Clarias macrocephalus x C. gariepinus) on native catfish populations in central Thailand. Aquaculture, 235:167-184

Shaji CP, Easa PS, Gopalakrishnan A, 2000. Freshwater fish diversity of Western Ghats. In: Ponniah AG, Gopalakrishnan A, eds. Endemic Fish Diversity of Western Ghats. NBFGR-NATP Publication. National Bureau of Fish Genetic Resources, Lucknow, India, 33-35

Singh AK, 2000. Impact of unauthorized exotic fish introduction on conservation and aquacultural development of the northeast region. In: Ponniah AG, Sarkar UK, eds. Proceedings of the National Workshop on northeast Indian fish Germplasm Inventory and Conservation, Meghalaya, India: NBFGR, India, 155-156

Teugels GG, 1986. A systematic revision of the African species of the genus Clarias (Pisces Clariidae). Ann. Mus. R. Afr. Centr. Sci. Zool., 247:199 pp

Tonguthai K, Chinabut S, Limsuwan C, Somsiri T, Chanratchakool P, Kanchanakhan S, MacRae IH, 1993. Handbook of Hybrid Catfish: Husbandry and Health. Aquatic Animal Health Research Institute, Kasetsart University, Bangkok, Thailand, 37 pp

Trzebiatowski R, Filipiak J, Sadowski J, 1993. Feeding of African catfish, Clarias gariepinus (Burchell, 1822) with feeds containing different fat levels. In: Carrillo M, Dahle L, Morales J, Sorgeloos P, Svennevig N, Wyban J, eds. Special Publication of the European Aquaculture Society no. 19, 279

Van Oijen MJP, 1995. Key to Lake Victoria fishes other than haplochromine cichlids, Appendix I. In: Witte F, Van Densen WLT, eds. Fish Stocks and Fisheries of Lake Victoria. A Handbook for Field Observations. UK: Samara Publishing Limited, 209-300

Van Weerd JH, 1995. Nutrition and growth in Clarias species: a review. Aquatic Living Resources, 8:395-401

Verreth JAJ, Eding EH, 1993. European farming industry of African catfish (Clarias gariepinus): Facts and figures. Aquaculture Europe, 18:6-13

Wedekind H, 1995. Growth, body composition and meat quality in African catfish from two pure breeds and one hybrid population. Advances in Fisheries Science, 12:107-116

Whitfield AK, Blaber SJM, 1979. Predation on stripped mullet (Mugil cephalus) by Crocodylus niloticus at St. Lucia, South Africa. Copeia, 1979(2):266-269

Distribution References

Bell-Cross G, Minshull JL, 1988. The fishes of Zimbabwe., Harare, National Museums and Monuments of Zimbabwe. 294 pp.

Beveridge MCM, Haylor GS, 1998. Warm-water farmed species. In: Biology of Farmed Fish, [ed. by Black KD, Pickering AD]. Sheffield Academic Press. 393-394.

CABI, Undated. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI

Eschmeyer WN, 2003. Catalog of fishes. Updated database version of March 2003. In: Catalog databases as made available to FishBase in March 2003,

FAO, 1997. FAO Database on Introduced Aquatic Species., Rome, Italy: Food and Agricultural Organization of the United Nations.

FAO, 2002. Aquaculture production: values 1984-2001. In: FAO Yearbook. Fishery statistics. Aquaculture production 2001, 92 (2) Rome, FAO.

Juliano RO, Guerrero R III, Ronquillo I, 1989. The introduction of exotic aquatic species in the Philippines. [Proceedings of the Workshop on Introduction of Exotic Aquatic Organisms in Asia: The Asian Fisheries Society], [ed. by De Silva SS]. 83-90.

Krupp F, Schneider W, 1989. The fishes of the Jordan River drainage basin and Azraq Oasis. In: Fauna of Saudi Arabia, 10 347-416.

Paugy D, Traoré K, Diouf PS, 1994. (Faune ichtyologique des eaux douces d’Afrique de l’Ouest). In: Biological diversity of African fresh- and brackish water fishes. Geographical overviews presented at the PARADI Symposium, Senegal, 15-20 November 1993. Ann. Mus. R. Afr. Centr., Sci. Zool. 275 [ed. by Teugels GG, Guégan JF, Albaret JJ]. 35-66.

Shaji CP, Easa PS, Gopalakrishnan A, 2000. Freshwater fish diversity of Western Ghats. In: Endemic Fish Diversity of Western Ghats. NBFGR-NATP Publication, [ed. by Ponniah AG, Gopalakrishnan A]. Lucknow, India: National Bureau of Fish Genetic Resources. 33-35.

Teugels GG, 1986. A systematic revision of the African species of the genus Clarias (Pisces Clariidae). In: Ann. Mus. R. Afr. Centr. Sci. Zool. 247 199 pp.

Links to Websites

WebsiteURLComment
GISD/IASPMR: Invasive Alien Species Pathway Management Resource and DAISIE European Invasive Alien Species Gatewayhttps://doi.org/10.5061/dryad.m93f6Data source for updated system data added to species habitat list.
Global register of Introduced and Invasive species (GRIIS)http://griis.org/Data source for updated system data added to species habitat list.
Planet Catfishhttp://www.planetcatfish.com

Contributors

Main Author
Wing-Keong Ng
Fish Nutrition Laboratory, School of Biological Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia


Contoh dan Manfaat Chordata (Invertebrata)

Meskipun dapat dimakan, namun Chordata yang tidak bertulang belakang bukanlah sumber makanan yang signifikan bagi manusia. Manfaat hewan ini yang terutama adalah untuk menyediakan petunjuk asal-usul Vertebrata dari sudut pandang evolusi. Selain itu, tunicata mengandung bahan kimia yang unik dan beberapa dapat dimanfaatkan sebagai obat. Berikut adalah contoh-contohnya:

1. Nanas Laut

  • Subfilum: Tunicata
  • Kelas: Ascidiacea
  • Ordo: Pleurogona
  • Subordo: Stolidobranchia
  • Familia: Pyuridae
  • Genus: Halocynthia
  • Spesies: Halocynthia roretzi

Dikonsumsi terutama di Korea dan Jepang.

  • Subfilum: Tunicata
  • Kelas: Ascidiacea
  • Ordo: Pleurogona
  • Subordo: Stolidobranchia
  • Familia: Pyuridae
  • Genus: Pyura
  • Spesies: Pyura chilensis
  • Subfilum: Cephalochordata
  • Kelas: Leptocardii
  • Ordo: Amphioxiformes
  • Familia: Branchiostomidae
  • Genus: Branchiostoma
  • Spesies: Branchiostoma lanceolatum

"Ikan" kecil ini (walaupun mungkin dari spesies berbeda B. japonicum atau B. belcheri) dikonsumsi di Xiamen dan populer dengan nama Wenchang.

  1. Wikipedia contributors, “Notochord,” Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/w/index.php?title=Notochord&oldid=719539877 (diakses 25 Mei 2016).
  2. Wikipedia contributors, “Chordate,” Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/w/index.php?title=Chordate&oldid=722563631 (diakses 31 Mei 2016).
  3. Mader, S. S., 2009, 󈬍.1 The Chordates,” Biology, 10th edition, McGraw-Hill, New York, NY.
  4. Raven et al., 2011, 󈬓.2 The Nonvertebrate Chordates,” Biology, 9th edition, McGraw-Hill, New York, NY.
  5. Reece et al., 2014, 󈬒.1 Chordates have a notochord and a dorsal, hollow nerve cord,” Campbell Biology, 10th edition, Pearson Education, Inc., U.S.
  6. Kontributor Tentorku, 2016, “Asal Usul Evolusi Chordata dan Vertebrata,” Artikel Tentorku, https://www.tentorku.com/evolusi-chordata-vertebrata/ (diakses 31 Mei 2016).
  7. Wikipedia contributors, “Lancelet,” Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/w/index.php?title=Lancelet&oldid=721470176 (diakses 31 Mei 2016).
  8. Wikipedia contributors, “Tunicate,” Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/w/index.php?title=Tunicate&oldid=722092987 (diakses 31 Mei 2016).

Kutip materi pelajaran ini:
Kontributor Tentorku, 2016, "Chordata Tak Bertulang Belakang (Invertebrata Chordata)," Artikel Tentorku, https://www.tentorku.com/karakteristik-klasifikasi-chordata-invertebrata/ (diakses pada 25 Jun 2021).

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