Animal body plans and classification

≈ 48 min

Animal body plans and classification

Animal groups can be compared using structural evidence: symmetry, number of tissue layers, body cavity, segmentation, support and digestive organisation. A classification becomes stronger when it uses several inherited traits rather than one visible feature or habitat. For example, a whale and a shark both live in water, but their skeletons, breathing and reproduction reveal different lineages.

Work it through

An animal has bilateral symmetry, a segmented body and jointed legs. These traits support classification as an arthropod. Saying only that it lives on land would not distinguish it from many unrelated animals.

Mastery target

Use at least two diagnostic traits to support a classification and reject a tempting but weak clue.

Which evidence is most useful for classifying an unfamiliar animal?

A set of body-plan traits

Whether it looks frightening

The colour of its habitat

Whether people keep it as a pet

Name the key biological term from Animal body plans and classification: enter the term that best fits the explanation and visual model.

Why are a dolphin and a shark not placed in the same major vertebrate group?

A dolphin is a mammal with lungs and live birth; a shark is a fish with gills.

They live in different oceans.

One is always larger.

Only sharks move.

Which statement corrects a common misunderstanding in Animal body plans and classification?

Correct: Similar habitats can produce similar features through adaptation; habitat alone does not prove close relatedness.

A single observation is enough to prove every biological claim.

Scientific terms are interchangeable whenever they sound similar.

A process always has exactly the same result in every environment.