Chapter 30.2, Problem 6MI

Summary Introduction

To Analyze:

The characteristics of monotremes by identifying their mammal-like and reptile-like features.

Introduction:

Monotremes animals included in subclass Prototheria. They share some characteristics mammal and some characters of their ancestor reptiles. Examples are duck-billed platypus and Echidna. They are only found in Australia, Tasmania and New Guinea.

Explanation of Solution

The mammalian and reptilian features of monotremes are given below:

Mammalian features:

Monotremes are warm-blooded vertebrates. Their body is covered with body hair or fur and secondly, their females have mammary glands to feed their young ones. The skin of many mammals is covered with sweat glands and they have a four-chambered heart.

Reptilian features:

Female monotremes lay eggs small, leathery eggs in a pouch. The babies hatch from the eggs. They have a single common opening for the digestive, urinary, and reproductive tract called the cloaca. The bone structure of the shoulder area is similar to reptiles. They have chromosomes of the mix of mammal-sized and reptile-sized chromosomes.

Conclusion

Monotremes are very primitive mammals which share some features of mammals and some features of their ancestor reptiles.