Video Transcript
An unknown marine organism is discovered. The organism found has a long, thin body that is not covered in scales, and it has no paired fins. What class of vertebrates is this organism most likely to belong to?
To answer this question, let’s look at vertebrates in more detail. Vertebrates can be split into five main groups, which share certain characteristics: fish, reptiles, amphibians, birds, and mammals. As this vertebrate is a marine organism, it is likely to belong to a group that is commonly known as fish. However, there are also marine organisms belonging to each of the other groups of vertebrates too.
There are three large classes of fish: class Agnatha, class Chondrichthyes, and class Osteichthyes. Organisms that belong to the class Agnatha are commonly known as jawless fish. These fish have long, thin bodies, a funnel-like mouth, and no paired fins. A common example of a fish belonging to this class would be a lamprey. Class Chondrichthyes are cartilaginous fish and include animals such as sharks and rays. These organisms have bodies covered in scales and have paired fins. Organisms belonging to class Osteichthyes have bony skeletons and bodies covered with scales. An example of a fish belonging to class Osteichthyes is a bolti.
If we look back at the question, we can see that the marine organism in the question has a long, thin body, no paired fins, and doesn’t have scales. So the most likely answer for this question is that the organism described belongs to class Agnatha.
