Phylum Chordata: Definition, Characteristics, Clarification and Role

sinaumedia Literacy – Chordata is a group of animals that have a backbone. Phylum chordata is a group of animals that includes vertebrates. However, not all chordates are vertebrates. Chordata comes from the Greek word “chorda” which means strings, strings, or ropes. Let’s get to know more closely the characteristics and classification of chordates along with a more complete explanation from Sinaumed’s!

DEFINITION OF CHORDATA

Chordata comes from the Greek word chorde which means strings or strings. As the name implies, members of the chordate group have an elongated notochord (corda dorsalis) as the axial framework of the body. These animals have the characteristics of multicellular, heterotrophic, eukaryotic, and do not have cell walls. Animalia are grouped into two major groups, namely Invertebrates which include Porifera, Coelenterata, Platyhelminthes, Nemathelminthes, Annelida, Molluscs, Arthropoda and Echinodermata, and Vertebrates including one phylum, namely Chordata.

The division of animals into these phyla is based on the number of layers of embryonic tissue, body cavity (coelom), habitat, limbs (fins, wings, legs and arms), completeness of organs (digestion, respiration, excretion, reproduction, nerves), presence or absence spinal column.

 

CHORDATA FEATURES

Chordata is an animal phylum that we can easily recognize by looking at its characteristics. Usually in animals chordates have four main characteristics that appear during embryonic development. Here are some of the characteristics of chordates that you need to know about Sinaumed’s:

  • Has a notochord, which is a supporting stalk or a kind of cartilage that extends dorsally, precisely under the nervous system. The notochord serves as a support for the body. In the embryonic stage all chordates and in the adult stage some species of chordates have a notochord.
  • The dorsal nerve cord (nervecord), is a tube derived from nerve fibers that develops into the central nervous system, which consists of the brain and spinal cord in vertebrates. In chordates, it is dorsal to the notochord. In contrast, other animal phyla are characterized by dense nerve cords that are located either ventrally or laterally.
  • Pharyngeal slit, is a gap or opening in the pharynx (the area just behind the mouth) that extends to the outside environment. In organisms that grow in aquatic habitats, this gap allows water to escape which enters the mouth when eating. In some chordate invertebrates, the pharyngeal slit is used as a filter for food from water entering the mouth, while in vertebrate fish this slit is modified or develops into a gill slits. Human embryos also have gills, but they disappear before we are born and tissue develops into other structures in the head and neck.
  • Post-anal tail, is the posterior extension of the body towards the anus. The tail contains skeletal and muscular components, thus helping to propel movement of aquatic animals such as fish. In vertebrates it is also used to provide balance, attract mates, and to signal when danger is near. The post-anal tail is also shrunken in humans and apes.
  • These animals already have digestive organs such as a mouth, pharynx, intestine, and anus. They are generally animals that feed by filtering food particles. The organ that functions to filter food is a ciliated indentation located in the pharynx (called the endostyle).
  • Reproduce sexually by external fertilization. Sperm and eggs are released into the water where fertilization will take place. While the majority of tunicates are hermaphrodites and reproduction can occur sexually or asexually (by budding).

 

CHORDATA CLASSIFICATION

Phylum Chordata is divided into three subphyla, namely Cephalochordata, Urochordata, and Vertebrata. Urochordata and cephalochordata are classified into a group of non-skulled chordates or called Arcania (Prochordata). The 3 subphyla in the Phylum Chordata include:

 

CEPHOCHORDATA (LANCELET)

Lancelet has a shape resembling a fish, but has no fins, transparent, elongated like a knife, and smaller body size. Because its body is like a knife, this animal is called a lancelet. Lancelet lives by burying his body in the sand on the bottom of a tropical sea, showing only his head. This animal uses its tentacles to bring food into its mouth.

 

UROCHORDATA (TUNICATE)

These animals live in the sea independently or parasites. The larval phase usually has four chordate structures, while the adults, although tunicates are classified as chordates, have lost the notochord, dorsal nerve cord, and post-anal tail, but they still retain the pharyngeal slits. Most tunicates are hermaphrodites. Tunicates feed on plankton and detritus. Example: Molgula sp, Botryllus sp.

 

HEMICHORDATA (UPDATE: No longer in Phylum Chordata)

Animals in the Hemichordata group have elongated worm-like bodies consisting of the proboscis, neck and body. The notochord is hollow, short, is a forward continuation of the alimentary canal and enters the proboscis. This animal has many gill slits on the lateral side. The nervous system includes dorsal and ventral nerves. The heart is located on the dorsal anterior side, equipped with dorsal blood vessels and ventral blood vessels. Gonochoris and fertilization occurs externally. These animals live in the sea, making burrows on the beach or in the deep sea. Example: Dolichoglossus sp (Balanoglosus, marine worm).

 

VERTEBRATA (CRANIATA)

Vertebrates have vertebrae as a development from the notochord. Habitat on land, fresh water and in the sea. Vertebrates have a well-defined head with a brain protected by a cranium. Has two pairs of jaws (except Agnatha), breathes with gills, lungs, and skin. Members of the motion in the form of fins, wings, legs and hands, but there are also those that do not have motion parts. Reproduction is sexual, separate sexes, external or internal fertilization, oviparous, ovoviviparous or viviparous. Vertebrata’s heart is well developed, divided into several chambers, their blood contains hemoglobin, so it is red. Vertebrates have a pair of eyes, generally also have a pair of ears. The Vertebrata subphylum consists of five classes, namely:

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PISCES CLASS

Pisces are aquatic animals, breathe with gills, sometimes there is a swimming bubble or air bubble as a breathing apparatus. The brain is covered by the cranium (headbone) in the form of cartilage or hard bone. Pisces blood flows from the heart through the gills to all body tissues and back again to the heart.

Tool locomotion in the form of fins, pronephros and mesonephros type kidneys. The body is covered by scales which act as the exoskeleton. Pisces reproduce sexually, oviparous (laying eggs). Based on the type of bones that build their body frame, Pisces (fish) are grouped into two groups, namely cartilaginous fish (Chondrichthyes), true bony fish (Osteichthyes) and jawless fish (Cyclostomata):

  • Cartilaginous fish (Chondrichthyes): The class Chondrichtyes contains approximately 850 species of fish. They have jaws, many teeth, paired fins, and an internal skeleton made of cartilage. This class of fish is considered a living fossil because it is a descendant of ancient animals that have inhabited the sea for hundreds of millions of years. Chondrichthyes fish have five to seven gill slits on either side of the pharynx and lack the gill flaps found in true bony fish. Some types of cartilaginous fish that can still be found today are sharks, stingrays, and lampreys. Sharks and rays are included in Chondrichthyes. Find interesting facts about sharks in the book Animal Anatomy Series: Sharks and Other Fish.
  • Bony fish (Osteichthyes): True bony fish have a skeleton made up of hard bones. There are about 20,000 species of true bony fish that can be found both in sea and in fresh water. Osteichthyes can be divided into two groups, namely Sarcopterygii and Actinopterygii. The most abundant species in this class of Osteichythyes fish are Actinopterygi fish. Some of the Actinopterygii fish are thought to be related to the ancestor of Amphibia. Examples of true vertebrate fish species include catfish (Ameiurus melas), eels (Anguilla sp), and goldfish (Cyprinus caprio). Look at the following picture. Goldfish and catfish belong to the Osteichthyes group
  • Agnatha (Cyclostomata): Agnatha includes jawless fish, having a round mouth, which is at the anterior end. No fins, but some types of Agnatha have caudal and dorsal fins. The notochord persists throughout life, imperfectly and covered with cartilage. The sexes are separate, some are hermaphrodites and get food by sucking the bodies of other fish with their mouths. Example: Myxine sp (ghost fish, hag fish), Petromyzon sp (lamprey, sea eel).

AMPHIBIA CLASS

This class includes 4,000 species of animals that undergo their larval stage in water and as adults live on land, therefore, are called Amphibia. Amphibians usually have to return to the water to mate and lay their eggs. Amphibians can adapt to nature in various ways, which are discussed in the book Why? The Reptiles and AMphibian – Reptiles and Amphibians.

Most adult amphibians have moist skin that helps their small, inefficient gas exchange lungs. Amphibians release their eggs into the water when external fertilization or fertilization occurs, as occurs in fish. Usually, Amphibia eggs are not protected by a shell, but are protected by a mucus.

Larvae generally change shape when developing into adult forms that live on land. Amphibians, like fish, are poikilothermic animals. That is, its body temperature can adapt to its environment. If the ambient temperature is too low, poikilothermic animals become less active. Examples of Amphibia species include toads (Bufo marmus), green frogs (Rana pipiens), and salamanders (Axolot). In Amphibians, the sexes are separate and reproduction is oviparous (egg-laying) Orders within Amphibians:

  • Order Caudata (Urodela) Caudata looks like a lizard, has a tail, breathes with lungs, some breathe with gills. His body is clearly divided into the head, body and tail. The legs are just as big. Example: Megalobatrachus japonius (giant salamander).
  • Order Salientia (Anura) is a nation of frogs, no tail, good at jumping. Adult animals breathe with lungs. The head and body of this animal are together, without a neck. The front legs are short, the hind legs are big and strong for jumping. Anura have swimming membranes on their toes. Undergoes metamorphosis, external fertilization. Example Bufo terrestris (frog frog), Rana pipiens (green frog).
  • Order Apoda (Gymnophiona) Worm-like animals, without legs. The skin is soft, between the eyes and nose there are tentacles that can be protruded. This animal has eyes without lids and a short tail. Male animals have copulation organs that can be highlighted. Breeding is oviparous or ovoviviparous. There are many Anura animals in the tropics. Example: Ichthyosis glutinosus.

Various Amphibia animals have interesting facts that you can learn in the DK Findout book! Reptiles And Amphibians which is definitely interesting.

CLASS REPTILIA

Reptilia comes from the Latin word, namely reptile which means snake. Reptiles are generally poikilothermic. Reptiles are also known as reptiles. Slithering is a way of walking by attaching the belly to the ground. Reptiles consist of approximately 6,000 species of animals, including snakes, lizards, turtles and crocodiles. Various facts about reptiles, such as why do lizards break off their tails? and why chameleons can change color are thoroughly discussed in the book Animal Anatomy Series: Crocodiles and Other Reptiles.

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Reptiles store their eggs which are protected by a thick shell and have an internal membrane. Reptiles carry out internal fertilization. Like Amphibia, Reptilia is also an animal that absorbs heat from its external environment. Examples of reptiles include pythons (Phyton reticulatus), Komodo dragons (Varanus komodoensis) and lizards (Lacerta agilis). Some reptiles have become extinct, for example Dinosaurus and Pterydactyla (winged reptiles). Orders within Reptilia:

  • The Chelonian order Chelonia includes turtles and tortoises. The body is wide, dorsally protected by the carapace (dorsal shield) and plastron (ventral shield). The jaws are toothless, but covered with a horny substance. The ribs are fused with the dorsal shield. Habitat Chelonia on land, seawater and fresh water. Oviparous breeding, eggs are laid in the holes made by the female animal. Example: Chelonia myotas (turtle), Chelydraserpentina (freshwater turtle).
  • Order Squamata Group of reptiles with scales, without abdominal ribs.
  • Order Crocodilia This order includes the crocodile class. This animal has thick skin, with abdominal ribs. The body is elongated, the head is large and long with strong jaws and teeth. Crocodilia live in fresh and sea water. A heart with a perfect ventricular septum. Oviparous reproduction, eggs are incubated in decaying leaves. Crocodilia has four legs, short, fingernails. Example: Crocodylus sp, Alligator sp.

Get to know and explore the world of animals with the book Pisces, Reptilia, Amphibians – Exploring the Animal World which discusses various interesting facts about reptiles that you want to know.

AVES CLASS

Class Aves (birds) consists of about 9,000 species. The entire body of the bird is covered in feathers, except for the legs and beak. Bird feathers and beaks are made of keratin. Birds do not have teeth to chew their food, but have a crop. Birds have wings that can help them fly. However, there are some birds that cannot fly, for example the cassowary and the ostrich. Birds as animals whose body temperature is fixed (homoothermic). Birds breathe with lungs. In addition, bird breathing is assisted by air sacs when flying. Birds fertilize inside the female’s body. After fertilization occurs, the birds will lay eggs and will incubate them until they hatch. Examples of Aves class species include native chickens (Gallus domestica), pigeons (Columba fasciata), sparrows (Passer montanus),

Further explanation about animals with Aves class species can be found in the book Aves Invertebrata – Exploring the Animal World, which you can get only at sinaumedia!

CLASS MAMALIA

Mammalia comes from the Latin word, namely mammae which means mammary gland. Class Mammalia consists of about 5,000 species which are grouped into 26 orders. Mammalia can reproduce by giving birth and laying eggs as discussed in the book Encyclopedia of the World of Mammals (FC).

Common characteristics of mammals are having hair, having three bones in the middle ear, and having mammary glands. Mammalia has a larger brain volume compared to other vertebrate animals.

Mammalia’s body temperature is fixed or not affected by the temperature of the external environment (homoothermic). Mammalia’s breathing apparatus is the lungs. Mammals also have high adaptability. Mammalia has many orders. Here are some orders in Mammalia as follows:

  • Monotremes (beaked mammals), for example Platypus (Ornitherynchus anatinus).
  • Carnivores (meat-eating mammals), for example cats (Felis domestica).
  • Rodentia (rodent mammals), for example mice and rats (Mus musculus).
  • Cetaceans (water mammals), for example whales (Balanoptera borealis).
  • Chiroptera (Mammalia with wings), for example bats (Myotes sp.).
  • Marsupials (Marsupial mammals), for example kangaroos (Macropus sp.).
  • Probosoidea (Mammalia proboscis), for example the elephant (Elephas maximus).
  • Primates, for example proboscis monkey (Nasalis larvatus).

BENEFITS OF CHORDATA

Although edible, chordates without backbones are not a significant food source for humans. The main benefit of these animals is that they provide clues to the origin of Vertebrates from an evolutionary point of view. In addition, tunicates contain unique chemicals and some can be used as medicine. Chordata is also used as a source of food ingredients, for example chicken meat or eggs and cow’s milk. As a raw material for the textile industry, for example the use of sheep hair to make wool As an object of research, for example Mammalia As a pet bird, for example cats, rabbits or birds. However, there are also several types of Chordata that are detrimental to humans, such as rats which can become pests of agricultural crops.

Thus, an explanation of the Definition, Characteristics, Clarification and Benefits of Chordata in Everyday Life. Hopefully this article can help you understand Chordata. Enjoy studying Sinaumed’s!

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