Types of
skeletal
systems
Reem Khaled
3B
Hydrostatic Skeletons
– A hydrostatic skeleton consists of fluid held under pressure in a
closed body compartment.
– A hydrostatic skeleton is a skeleton formed by a fluid-filled
compartment within the body, called the coelom.
– This is the main type of skeleton in most cnidarians, flatworms,
nematodes, and annelids
– These animals control their form and movement by using muscles to
change the shape of fluid-filled compartments.
– Among the cnidarians, for example, a hydra elongates by closing its
mouth and using contractile cells in its body wall to constrict its
central gastrovascular cavity
– Worms use hydrostatic skeletons in diverse ways to move through
their environment.
– In planarians and other flatworms, movement results mainly from
muscles in the body wall exerting localized forces against the
interstitial fluid.
– In earthworms and many other annelids, circular and longitudinal
muscles act together to change the shape of individual fluid-filled
segments, which are divided by septa.
– These shape changes bring about peristalsis, a movement
produced by rhythmic waves of muscle contractions passing from
front to back
Hydrostatic Skeletons
– Hydrostatic skeletons are well suited for life in aquatic
environments.
– On land, they provide support for crawling and
burrowing and may cushion internal organs from shocks.
– However, a hydrostatic skeleton cannot support walking
or running, in which an animal’s body is held off the
ground.
Exoskeletons
– It is a hard encasement deposited on an animal’s attached to
knobs and plates of the cuticle that extend into the interior of the
body.
– With each growth spurt, an arthropod must shed its exoskeleton
(molt) and produce a larger one.
– . Arthropods such as crabs and lobsters have exoskeletons that
consist of 30–50 percent chitin, a polysaccharide derivative of
glucose that is a strong but flexible material. Chitin is secreted by
the epidermal cells.
– https://i.imgur.com/S9Q9D5y.mp4
– The exoskeleton is further
strengthened by the addition of
calcium carbonate in organisms
such as the lobster. Because the
exoskeleton is acellular,
arthropods must periodically
shed their exoskeletons because
the exoskeleton does not grow as
the organism grows.
Endoskeletons
– Animals ranging from sponges to mammals have a hardened
internal skeleton, or endoskeleton, buried within their soft
tissues.
– In sponges, the endoskeleton consists of hard needlelike
structures of inorganic material or fibers made of protein.
Endoskeletons
– Chordates have an endoskeleton consisting of cartilage,
bone, or some combination of these materials
– The mammalian skeleton is built from more than 200 bones, some
fused together and others connected at joints by ligaments that
allow freedom of movement
Resources
– Human Biology
– https://bio.libretexts.org/TextMaps/Introductory_and_General_Biology/Book%
3A_General_Biology_(OpenStax)/7%3A_Animal_Structure_and_Function/38%3
A_The_Musculoskeletal_System/38.1%3A_Types_of_Skeletal_Systems
– https://courses.lumenlearning.com/boundless-biology/chapter/types-ofskeletal-systems/
– https://study.com/academy/lesson/hydrostatic-skeletons-exoskeletonsendoskeletons.html
– https://www.siyavula.com/read/science/grade-10-lifesciences/supportsystems-in-animals/06-support-systems-in-animals-02
– https://www.dummies.com/education/science/biology/types-skeletal-systems/