Question

Fish or Mammals? Argumentation

Background
You have seen several lines of evidence that scientists have used to understand where cetaceans
fit on the animal family tree. In the practice of scientific argumentation, pieces of evidence are used
to support claims. Reasoning is the logical thinking and science ideas that connect claims and
evidence.
Instructions
You will need the following handouts:
• Fish or Mammals? Case study
• Fish or Mammals? Evidence organizer
Using the handouts, find the evidence that connects each claim to the reasoning, and add it to the
table. Keep in mind that a well-substantiated claim may later become evidence or reasoning for
another claim.
For Type of Evidence, fill in whether it is from anatomy (A), embryological development (E), fossils
(F), or DNA (D). (Amino acid sequences, because they are coded in DNA, are DNA evidence.)
In some cases, there are multiple types of supporting evidence.​

Answer 1

To determine whether cetaceans (whales, dolphins, and porpoises) are more closely related to fish or mammals, scientists use evidence from anatomy, embryological development, fossils, and DNA. The evidence includes anatomical features, fossil records, and genetic similarities, all of which support the conclusion that cetaceans are mammals. Therefore, the reasoning connecting the claims about cetaceans being mammals is well-supported by scientific evidence.

Step-by-step explanation:

Fish or mammals? To determine whether cetaceans (whales, dolphins, and porpoises) are more closely related to fish or mammals, scientists use evidence from anatomy, embryological development, fossils, and DNA. Each type of evidence provides support for the reasoning connecting claims about the evolutionary position of cetaceans on the animal family tree.

For example, anatomical features such as the presence of mammary glands, the ability to breathe air, and the presence of hair during embryonic development all suggest that cetaceans are mammals. Fossil evidence shows the gradual transition of land-dwelling ancestors to fully aquatic animals. DNA evidence reveals genetic similarities between cetaceans and other mammals.

In conclusion, the evidence of anatomy, embryological development, fossils, and DNA all points to cetaceans being mammals rather than fish. Therefore, the reasoning connecting the claims about cetaceans as mammals is well-supported by scientific evidence.

Answer 2

Mammals

Step-by-step explanation: