Blue Sky Science: What makes a mammal? Is an octopus a mammal?

Austin Shiffler


What makes a mammal? Is an octopus a mammal?

It’s a great guess, but an octopus is not a mammal. An octopus is an invertebrate animal, which means it has no spine. More specifically, an octopus is a cephalopod, like squid and cuttlefish. They’re some of the smartest invertebrates.

Mammals like giraffes, on the other hand, are vertebrate animals, which means they have spines. They’re also warm-blooded, so they produce their own body heat rather than relying on their environment for their body heat. Mammals also make milk for their young and have either fur or hair.

There are many animals at the Henry Vilas Zoo. All visitors have their particular favorite, though mammals tend to be the most popular.

The zoo has some primates, big cats, grizzly bears and even some marine mammals like polar bears and harbor seals.

Many people think that giving live birth is also a characteristic of mammals. While giving live birth is a characteristic of most mammals, there are exceptions to the rule.

The egg-laying platypus and the echidna, also known as a spiny anteater of Australia, are very ancestrally old mammals. They lay eggs instead of giving live birth. They’re still considered mammals because they’re warm-blooded, vertebrate animals with fur that make milk for their young.