EVERYDAY SCIENCE

Detailed explanation-1: -Many soft-bodied organisms or parts of organisms (e.g. terrestrial and marine worms, cnidarians, echinoderms, bivalves, gastropods and nematodes) possess a hydrostatic skeleton. Hydrostatic skeletons are characterized by a liquid-filled internal cavity surrounded by a muscular body wall (Kier, 2012).

Detailed explanation-2: -The hydrostatic skeleton of some animals, such as worms, encompasses their entire body, whereas in others it is used only for a specific organ, as in the elephant trunk.

Detailed explanation-3: -In arthropods the skeleton is formed in part by the cuticle covering the body surface, by internal connective-tissue fibres, and by a hydrostatic skeleton formed by the hemocoele, or enlarged blood-filled spaces. The cuticle may be flexible or stiff, but it does not stretch.

Detailed explanation-4: -Vertebrates are animals that have backbones and an endoskeleton (skeleton inside their bodies). In contrast, invertebrates are animals that do not have backbones. Invertebrates can have a skeleton outside their bodies called an exoskeleton, while some invertebrates have no skeleton at all!

Detailed explanation-5: -Hydrostatic Skeleton This type of skeletal system is found in soft-bodied animals such as sea anemones, earthworms, Cnidaria, and other invertebrates (Figure 1). Movement in a hydrostatic skeleton is provided by muscles that surround the coelom.