Are Agnatha Chondrichthyes?
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 are two Agnatha examples?
Agnatha are jawless fish. Lampreys and hagfish are in this class.
What do osteichthyes and Chondrichthyes have in common?
Similarities Between Chondrichthyes and Osteichthyes Both have both endoskeleton and exoskeleton. Breathing of both fish occurs through gills. They have a mouth with jaws. Their fins are paired.
How many species of Agnatha are there?
The oldest fossil agnathans appeared in the Cambrian, and two groups still survive today: the lampreys and the hagfish, comprising about 120 species in total.
What are the characteristics of 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 are lampreys and hagfish different?
Hagfish is an eel-like slime producing marine jawless fish while lamprey is an eel-like jawless fish that lives in coastal and freshwaters. Hagfish does not possess vertebra while lamprey has vertebra. Hence, hagfish is not considered as a vertebrate while lamprey is a vertebrate.
Are hagfish and lampreys vertebrates?
Hagfish and lampreys are the only living representatives of the jawless vertebrates (agnathans), and compared with jawed vertebrates (gnathostomes), they provide insight into the embryology, genomics, and body plan of the ancestral vertebrate.
What is the three characteristics of class Agnatha?
Class Agnatha (Jawless fish) Have no fins, no scales, and no jaw.
What are the five main differences between Chondrichthyes and Osteichthyes?
| Class- Chondrichthyes | Class- Osteichthyes |
|---|---|
| 1. The mouth is positioned ventrally and the body is covered with placoid scales. | 1. The mouth is positioned apically and body is covered with cycloid or ctenoid or ganoid scales |
What characteristics are specific to Osteichthyes Chondrichthyes?
| Characters | Chondrichthyes | Osteichthyes |
|---|---|---|
| Endoskeleton | Cartilaginous endoskeleton | Bony endoskeleton |
| Size | Large body | Smaller in size compared to Chondrichthyes |
| Position of mouth | Ventrally | Terminal |
| Scales | Placoid scales are present | Cycloid scales are present |
What is the difference between Agnatha and Gnathostomata?
The key difference between Agnathans and Gnathostomata is that Agnathans are organisms that do not possess a jaw while Gnathostomata are organisms with jaws. Agnathans are jawless fish. Gnathostomata are fish that have jaws. Both agnathans and Gnathostomata are very important in determining evolutionary relationships.