Question

Milk glands are characteristics of

• A. All vertebrates
• B. Only mammals
• C. Only placental mammals
• D. Only ruminants

Answer 1

Answer: (B)

Only mammals

Mammary glands are only found on mammalian species, and no other species. These are exocrine glands are enlarged and modified sweat glands and are the characteristic of mammals which gave the class its name. Only female mammals produce milk, an adaptation that requires an investment of time and energy to care for the newborn offspring.