Question

Write four salient features of cyclostomes.

Answer 1

Hint: Cyclostomata is a class of agnathans made up of live jawless fish. They include jawless mouths with horny epidermal systems that act like teeth and branch arches that are internally located.

Complete Answer:
- Cyclostomata is the modified and degenerate offshoot of the basal vertebrate stalk. They're called Cyclostomata because of their circular mouth. They are parasitic, generally feeding on fish in maturity. Morphologically, they look like eels. They are considered to be the only surviving vertebrates lacking true jaws, so-called Agnatha.
- Cyclostomata contains hagfish and lamprey. These fish are distinguished by a long slender body with no scales and fins, and the round jawless mouth with horny teeth, and a cartilaginous skull. There are no paired fishes. Median fin and cartilaginous fin rays. Few of their characteristics are they do not have a pair of fins. They have median fins with cartilaginous fin rays.
- Unlike the fish, there are no jaws found in their buccal cavity. They are therefore known as agnatha. Unlike fish, they have no scales on their bodies, even though they are marine creatures. They don't have an exoskeleton in their bodies. The endoskeleton is free of bone.
- It's made entirely of cartilages. They do not have a spleen.
- The most important part of any living organism is a brain, which is invisible in cyclostomes. There are around five to sixteen pairs of gills which are used for respiration. It consists of around ten pairs of cranial nerves.

Note: Cyclostoms are subdivided into two main orders, Petromyzontiformes and Myxiniformes. Lampreys or lamp eels correspond to Petromyzontiformes. Hagfishes are the Myxiniformes.