Question

Mammals share several characteristics, which distinguish them from all other classes of vertebrates. Check all of the features that one would use to classify members into this class.

a) Hair or fur
b) Laying eggs
c) Mammary glands
d) Warm-bloodedness

Answer 1

The class Mammalia is characterized by the presence of hair or fur and mammary glands. While mammals are warm-blooded, laying eggs is not a common feature for the class, except for the unique case of monotremes.

Step-by-step explanation:

The features one would use to classify members into the class Mammalia are a) Hair or fur and c) Mammary glands. Mammals are defined by these distinct attributes, along with being warm-blooded vertebrates. However, not all mammals lay eggs, so laying eggs, as a general characteristic, does not define the mammalian class.

Female mammals possess mammary glands which produce milk for their offspring. Hair or fur is present in all mammals, although it may not be extensive in some species like whales. Mammals are indeed endothermic, regulating their own body temperature regardless of the environment. Interestingly, the group of mammals called monotremes, which includes species like the platypus, do lay eggs, which is an exception among mammals.

While the class Mammalia is very diverse in form and habitat, the presence of mammary glands for lactation and hair or fur are consistent characteristics across all species within this class, indicating a shared evolutionary heritage.