skeletons and muscles

Skeleton

Any structure that maintains body shape, supports and protects a body, and transmits contractile forces.

Types of skeletons

Hydrostatic skeleton, exoskeleton, and endoskeleton.

Hydrostatic skeleton

The most widespread form of skeleton across Bilateria, associated with a fluid-filled body cavity.

Coelomate

Organisms that possess a coelom filled with coelomic fluid which separates intestines and organs.

Pseudocoelomate

Organisms that have lost their coelom and replaced it with a pseudocoelom.

Muscle structure

Includes longitudinal muscles and circular muscles; muscles can only contract and cannot push.

Molluscan exoskeleton

Exoskeleton in the form of a calcareous shell that protects soft-bodied animals.

Epicuticle

The hardened outer layer of the arthropod exoskeleton made of waxy lipoprotein, waterproof and acts as a barrier.

Osteoblasts

Bone cells responsible for producing new bone.

Endochondral ossification

Bone development that occurs from a cartilage precursor.

Fibrocartilage

Cartilage that is reinforced with collagen fibers and found in areas subjected to tensile or compressive forces.

Vertebrate skeletons

Support the body against external forces and allow muscles to develop forces for movement.

Mutable connective tissues

Echinoderms can reversibly vary the rigidity of their dermis and general connective tissue.

Splanchnocranium

Part of the vertebrate skeleton that includes the primary palate and jaws.

Chondrocytes

Cartilage cells that are housed within lacunae in the cartilage matrix.

Aponeuroses

Tendons drawn out into thin, flat sheets of connective tissue for muscle attachment.

Cartilaginous skeleton

The skeleton type of basal vertebrates, primarily made of cartilage.

Endoskeleton

A solid internal skeleton made of cartilage or bone, supporting the body.

Segmental muscle blocks

Muscle arrangement inherited from chordate ancestors, typical in vertebrates.