What type of reproduction do Agnatha have?

What type of reproduction do Agnatha have?

Lampreys reproduce in freshwater riverbeds, working in pairs to build a nest and burying their eggs about an inch beneath the sediment. The resulting hatchlings go through four years of larval development before becoming adults.

What makes Agnatha unique?

Evolution. If evidence from fossil and living forms is combined, the Agnatha are distinguishable from the other craniates (Gnathostomata) by what they lack: jaws, lateral fins supported by fin rays, vertebrae, a horizontal semicircular canal in the ear, and genital ducts.

How are lampreys different from other groups of fishes?

Once grown, most jawless fish have a skeleton made of cartilage and paired gill pockets (in some cases as many as seven). Being jawless, lampreys still have cartilaginous teeth and most being parasitic latch on and suck tissue and fluids from any fish they are attached to.

What are the peculiar features of respiratory system of Agnatha?

They have seven gill slits where oxygen diffuse. Agnatha breathe by sucking in water through the mouth and into the pharynx, then release water from the gill slits. Before leaving through the gill slits, water must pass through the feather-like gills.

Are Agnatha oviparous or viviparous?

Live-bearing (ovoviviparous).

How do Agnatha fish differ from Osteichthyes fish?

The bony fish differ from the Agnatha because they have jaws. The bony fish differ from the Chondrichthyes because the bony fish have skeletons made of bone. Most bony fish have scales, some have armor plating, and others, such as the catfish, lack any kind of covering over the skin and thus are completely naked.

What is the respiratory system of a Agnatha?

Gas Exchange/ Respiration They have seven gill slits where oxygen diffuse. Agnatha breathe by sucking in water through the mouth and into the pharynx, then release water from the gill slits. Before leaving through the gill slits, water must pass through the feather-like gills.

What are the differences between Agnatha and Chondrichthyes?

What are the nine main characteristics of the class Agnatha?

Key Features of Agnatha

• Jaws are absent.
• Paired fins are generally absent.
• Early species had heavy bony scales and plates in their skin, but these are not present in living species.
• In most cases the skeleton is cartilaginous.
• The embryonic notochord persists in the adult.
• Seven or more paired gill pouches are present.

How many classes are there in Agnatha?

There are two major groups of living agnathans, the lampreys and the hag-fish. Both appear fishlike or eel-like.