Summary
Hydrostatic skeletons, exoskeletons and endoskeletons give support and enable movement.
In depth
Hydrostatic (worms, cnidarians), exoskeletons (arthropods, molluscs) and endoskeletons (vertebrates, echinoderms). Bones store calcium and produce blood cells.
Skeleton type affects movement and size. Endoskeletons grow with the animal. Exoskeletons limit growth.
Key idea: skeletons support, protect and anchor muscles.
Hydrostatic skeletons use fluid enclosed by muscles, giving flexible movement but little support on land, as in earthworms and sea anemones. Exoskeletons protect but limit growth, and their weight is a constraint. Endoskeletons grow with the animal, and bone is a living tissue that remodels and repairs, storing calcium and phosphate and housing marrow. Cartilage is lighter and more flexible, forming the skeleton of sharks.
Bone cells include osteoblasts (build), osteoclasts (resorb) and osteocytes (maintain), regulated by hormones such as parathyroid hormone, calcitonin and vitamin D. Osteoporosis is bone loss. Skeletons also fossilise, giving a record of evolution.
Example: bird bones are hollow with internal struts, which gives strength with low weight.
Frequently asked questions
What is Animal Skeletons?
Hydrostatic skeletons, exoskeletons and endoskeletons give support and enable movement.
Which area of biology covers Animal Skeletons, and how advanced is it?
Animal Skeletons is one of the 53 topics in Zoology & Animal Diversity. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Vertebrates and Invertebrates, Body Cavities, Roundworms.
Can you give an example of Animal Skeletons?
Sharks have cartilage skeletons that are lighter and more flexible.
What should I learn before Animal Skeletons?
Work through the Beginner topics in Zoology & Animal Diversity first, such as Animal Kingdom, Vertebrates and Invertebrates, Sponges, then return to Animal Skeletons. Intermediate topics assume the Beginner vocabulary.
What topics are related to Animal Skeletons?
The closest topics to Animal Skeletons are Vertebrates and Invertebrates, Body Cavities, Roundworms, Protostomes and Deuterostomes. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Animal Skeletons?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Animal Skeletons. To practise the whole of Zoology & Animal Diversity, use the Zoology & Animal Diversity quiz.
How is Animal Skeletons different from Vertebrates and Invertebrates?
Animal Skeletons: Hydrostatic skeletons, exoskeletons and endoskeletons give support and enable movement. Vertebrates and Invertebrates: Vertebrates have a backbone; invertebrates, which are over 95 percent of animals, do not. Read both side by side and note what each one explains.
How should I study Animal Skeletons step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Vertebrates and Invertebrates and explain the difference aloud. Finally, take the Zoology & Animal Diversity quiz and come back to this page for any question you miss.