Classification of agnatha
What are the classes of Agnatha?
agnathan, (superclass Agnatha), any member of the group of primitive jawless fishes that includes the lampreys (order Petromyzoniformes), hagfishes (order Myxiniformes), and several extinct groups.
What is a characteristic of the class Agnatha?
Class Agnatha consists of an ancient group of animals similar to fish but with some very noticeable differences. The agnathans lack jaws and paired fins. Instead of jaws, they have a cyclostomic (circular) toothed mouth with which they bore into the side of a fish and suck the blood of their victim.
What are the 2 main examples of Agnatha?
The only surviving agnaths today are lampreys (class Cephalaspidiformes) and hagfishes (class Myxini). Lampreys and hagfishes are slimy; they completely lack scales or armor and are long and eel-like. The living representatives of this group survive as parasites and scavengers on other fish.
Which class belongs to Division Agnatha?
Division Agnatha includes just one class – Cyclostomata. Examples of this jawless class are lamprey and hagfish. Fishes are jawed, and are grouped under division Gnathostomata.
What are three characteristics of jawless fish?
Features of the jawless fish include a notochord, paired gill pouches, a pineal eye, and a two-chambered heart.
What are the two classes of jawless fish?
There are two categories of jawless fish: hagfish and lampreys. Hagfish usually feed on dead or dying fish.
What is the example of Agnatha?
Jawless fish/Lower classifications
Are Agnatha Oviparous or viviparous?
Live-bearing (ovoviviparous).
What is the scientific name for jawless fishes?
What characteristics separate agnathan fishes from other fishes?
A defining feature of agnathans is the lack of paired lateral appendages or fins. Some of the earliest jawless fishes were the ostracoderms (Greek for “bone-skin”). Ostracoderms were vertebrate fishes encased in bony armor, unlike present-day jawless fishes, which lack bone in their scales.
How do the class Agnatha breathe?
“Water breathing” through gills which are modified pharyngeal slits. (gas exchange between water and blood). Gills can absorb lower concentrations of available oxygen.
What are the characteristics of the class Osteichthyes?
Class – Osteichthyes
Like all fishes, Osteichthyes are cold-blooded vertebrates that breathe through gills and use fins for swimming. Bony fishes share several distinguishing features: a skeleton of bone, scales, paired fins, one pair of gill openings, jaws, and paired nostrils.
Are Agnatha Oviparous or viviparous?
Live-bearing (ovoviviparous).
Does Agnatha have heart?
The Agnatha are ectothermic, or cold-blooded, having a cartilaginous skeleton and a two-chambered heart. Skin covers the body of contemporary agnathans, with no dermal or epidermal scales. Hagfish have many slime glands on their skin, which act as a defensive mechanism.
What is an example of Agnatha?
Jawless fish/Lower classifications
What are the 3 classifications of fish?
Fishes are typically divided into three groups: superclass Agnatha (jawless fishes), class Chondrichthyes (cartilaginous fishes), and superclass Osteichthyes (bony fishes). The latter two groups are included within the infraphylum Gnathostomata, a category containing all jawed vertebrates.
Do Agnatha have bones?
Most agnathans have a skeleton made of cartilage and seven or more paired gill pockets. They have a light sensitive pineal eye. A pineal eye is a third eye in front of the pineal gland. Fertilization of eggs takes place outside the body.
How do Agnatha digest food?
Feeding/Digestion
Agnatha excrete enzyme and secretions near the buccal cavity (mouth) that break down the hosts blood to prevent it from clotting. The end portion of the intestine digests bacteria, reabsorbs water, and form feces. The last section of the intestine narrows to form a small exit.
Do Agnatha have fins?
Appendages. Almost all agnathans, including all extant agnathans, have no paired appendages, although most do have a dorsal or a caudal fin. Some fossil agnathans, such as osteostracans and pituriaspids, did have paired fins, a trait inherited in their jawed descendants.
What are the 5 classes of fish?
There are about 28,000 existing species of fish, and they are placed in five classes: hagfish, lampreys, cartilaginous fish, ray-finned bony fish, and lobe-finned bony fish.
Which animal is jawless?
Cyclostomes are a monophyletic group of eel-shaped animals that include modern hagfish and lampreys. Members of both groups have cartilaginous skulls, qualifying them as true crown-group vertebrates, but lack jaws. In fact, they are the only two groups of extant vertebrates that lack jaws.