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The skeletal system is made from bones and joints. The femur bone in the thigh is the longest and strongest bone in the body. The smallest bones in the body are called the ossicles in the...
- What does your skeleton do? - BBC Bitesize
The skeleton. Many animals have skeletons to support and...
- What does your skeleton do? - BBC Bitesize
- Overview
- Comparative study of skeletal systems
- Principal types of skeletal elements
skeleton, the supportive framework of an animal body. The skeleton of invertebrates, which may be either external or internal, is composed of a variety of hard nonbony substances. The more complex skeletal system of vertebrates is internal and is composed of several different types of tissues that are known collectively as connective tissues. This ...
In addition to its supportive function, the animal skeleton may provide protection, facilitate movement, and aid in certain sensory functions. Support of the body is achieved in many protozoans by a simple stiff, translucent, nonliving envelope called a pellicle. In nonmoving (sessile) coelenterates, such as coral, whose colonies attain great size, it is achieved by dead structures, both internal and external, which form supporting axes. In the many groups of animals that can move, it is achieved either by external structures known as exoskeletons or by internal structures known as endoskeletons. Many animals remain erect or in their normal resting positions by means of a hydrostatic skeleton—i.e., fluid pressure in a confined space.
The skeleton’s protective function alone may be provided by structures situated on the body surface—e.g., the lateral sclerites of centipedes and the shell (carapace) of crabs. These structures carry no muscle and form part of a protective surface armour. The scales of fish, the projecting spines of echinoderms (e.g., sea urchins), the minute needlelike structures (spicules) of sponges, and the tubes of hydroids, all raised from the body surface, are similary protective. The bones of the vertebrate skull protect the brain. In the more advanced vertebrates and invertebrates, many skeletal structures provide a rigid base for the insertion of muscles as well as providing protection.
The skeleton facilitates movement in a variety of ways, depending on the nature of the animal. The bones of vertebrates and the exoskeletal and endoskeletal units of the cuticle of arthropods (e.g., insects, spiders, crabs) support opposing sets of muscles (i.e., extensors and flexors). In other animal groups the hydrostatic skeleton provides such support.
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In a limited number of animals, the hard skeleton transmits vibrations that are sensed by the hearing mechanism. In some forms—e.g., bony fishes and fast-swimming squids—it aids in the formation of buoyancy mechanisms that enable the animal to adjust its specific gravity for traveling at different depths in the sea.
Certain types of skeletons usually characterize particular animal phyla, but there are a limited number of ways in which an animal can form its skeleton. Similar modes of skeleton formation have evolved independently in different groups to fulfill similar needs. The cartilaginous braincase of the octopus and the squid, which are invertebrates, has a microscopic structure similar to the cartilage of vertebrates. The calcareous (i.e., calcium-containing) internal skeleton of the echinoderms is simply constructed but is essentially not far different from the much more elaborate bones of vertebrates. Skeletal fibres of similar chemical composition occur in unrelated animal groups; for example, coiled shells of roughly similar chemical composition are present in gastropods (e.g., snails), brachiopods (e.g., lamp shells), and cephalopods (e.g., chambered nautilus). The mechanical properties of different skeletal types vary considerably according to the needs of animals of particular size ranges or habits (e.g., aquatic, terrestrial).
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Skeletal elements are of six principal types: hard structures, semirigid structures, connective tissue, hydrostatic structures, elastic structures, and buoyancy devices.
Jan 12, 2023 · Quick overview: bones are the principal components of the animal skeletal system that form the hard framework known as the skeleton. The skeleton of the animals is divided into two major parts – axial and appendicular skeletons.
Mar 15, 2024 · the main bones of the fore and hind limbs, and their girdles and be able to identify them in a live cat, dog, or rabbit. Fish, frogs, reptiles, birds and mammals are called vertebrates, a name that comes from the bony column of vertebrae (the spine) that supports the body and head.
The skeleton. Many animals have skeletons to support and protect their body and to help it move. The human skeleton is made of bones and grows as we grow. Our skull protects our brain and our...
The skull of humans includes a total of 29 bones: 8 cranial bones which make up the rounded top of the skull and protect the brain, 14 facial bones that help to protect the mouth and nose, 6 auditory bones which help mammals to hear sounds and 1 hyoid bone that supports the tongue.
Jan 15, 2021 · Definition. The skeletal system provides support and protection for the body’s internal organs and gives the muscles a point of attachment. Humans have an endoskeleton, where our bones lie underneath our skin and muscles. In other animals, such as insects, there is an exoskeleton on the outside of the body. Overview.
