Video Transcript
A scientist makes the following
notes on an organism. (1) Has a body covered in
scales. (2) Uses the environment to
regulate body temperature. (3) Breathes through lungs. Which class of vertebrates does
this organism most likely belong to?
To answer this question, we need to
look at the features that help us to distinguish between the different classes of
vertebrates so that we can decide which class this organism would best fit into. The three characteristics that the
scientist has noted can help us to distinguish different vertebrates from one
another. Let’s try to order the different
vertebrate classes into this decision tree to see which class has all three
features.
The three classes of vertebrate
fish, class Agnatha, class Chondrichthyes, and class Osteichthyes, are all found in
aquatic environments and breathe through gills or gill slits and not lungs like the
organism in question. So, we know that it does not belong
to these classes of vertebrates.
Organisms belonging to class Aves
and class Mammalia, which are the birds and the mammals, do breathe through
lungs. They can regulate their own body
temperature independently of the environment, therefore, generally do not use the
environment to regulate their body temperature. As we know that the organism in
question does use the environment to regulate body temperature, it cannot belong to
class Aves or class Mammalia.
Organisms belonging to class
Amphibia usually have lungs and do use the environment to regulate their body
temperature. However, amphibians have smooth
skin, so lack the scales described in the question. Therefore, our organism doesn’t fit
with this group either. This leaves us with the final
class, which is class Reptilia. Reptiles also breathe through
lungs. Organisms belonging to this class
include lizards and snakes, and they use the environment to regulate their body
temperature. Reptiles have a body covered in
scales, so our organism best fits in this group. This means that the answer to this
question is class Reptilia.
