hydrostatic skeleton
Liquid-supported body structure
A hydrostatic skeleton is an internal support system found in soft-bodied animals like earthworms, jellyfish, and sea anemones.
Rather than rigid bones, it uses fluid-filled compartments surrounded by muscle.
When muscles contract against the incompressible fluid, the pressure creates movement and maintains body shape: The earthworm moves by alternately squeezing segments of its hydrostatic skeleton.
Mesoderm-lined internal space
- body cavityEnclosed space holding organs
- musculatureArrangement of muscles
- soft-bodiedLacking internal skeleton
- turgiditySwollen or inflated state
support structure · compartmentalization · segmentation · peristalsis · incompressibility · body plan · structural support
Segmented soil-dwelling invertebrate
- jellyfishDrifting marine stinger
- octopusEight-limbed sea mollusk
- nematodeThreadlike parasitic worm
- cnidarianStinging aquatic invertebrate
sea anemone · squid · cuttlefish · leech · polychaete · caterpillar · slug · starfish
Study of pressurized liquids
- pressureForce upon contact
- turgorCellular fluid pressure
- incompressibleCannot be made smaller
- fluid dynamicsScience of flowing matter
elasticity · tension · compliance · energy transfer · mechanical advantage · pressure gradient · load bearing · flexibility
Digging to create shelter
- peristalsisInvoluntary digestive muscle waves
- crawlingMoving on hands, knees
- extensionAdded part or duration
- contractionReduction in size
jet propulsion · undulation · elongation · shortening · digging · swimming · creeping · anchoring
coelom
Mesoderm-lined internal space
- body cavityEnclosed space holding organs
- musculatureArrangement of muscles
- soft-bodiedLacking internal skeleton
turgidity · support structure · compartmentalization · segmentation · peristalsis · incompressibility · body plan · structural support
earthworm
Segmented soil-dwelling invertebrate
cnidarian · sea anemone · squid · cuttlefish · leech · polychaete · caterpillar · slug · starfish · sea cucumber
hydraulics
Study of pressurized liquids
- pressureForce upon contact
- turgorCellular fluid pressure
- incompressibleCannot be made smaller
fluid dynamics · elasticity · tension · compliance · energy transfer · mechanical advantage · pressure gradient · load bearing · flexibility · deformation
burrowing
Digging to create shelter
- peristalsisInvoluntary digestive muscle waves
- crawlingMoving on hands, knees
- extensionAdded part or duration
contraction · jet propulsion · undulation · elongation · shortening · digging · swimming · creeping · anchoring
- invertebrate anatomyantennae, gills, ganglia, nerve cord, cuticle
- worm anatomysetae, clitellum, segments, coelom, bristles
- animal traitsfur, tail, claws, teeth, wings
- aquatic adaptationsgills, fins, swim bladder, flippers, webbed feet
- cnidarianssea anemone, corals, stony coral, moon jelly, jellyfish
- body planbody plan, bilateral symmetry, radial symmetry, segmentation, body segments
hydrostatic skeletonendoskeleton
Body's inner framework
exoskeleton · bone structure · skeletal framework · spinal column
skeleton, static, skeletal, skeletons, exoskeleton, hydro, hydrostatics, endoskeleton, hydrostatic