1. Apply Concepts How do muscles enable movement

CH 28 ANIMAL SYSTEMS II28.2 Movement and Support

To move all animals must:1. Generate physical force2. Apply that force against air, water, or land in

order to push or pull themselves around.

Animals have three main kinds of skeletal systems: Hydrostatic skeletons Exoskeletons Endoskeletons.

Hydrostatic Skeletons

Consists of fluids held in a gastrovascular cavity Alters the body’s shape drastically by working with

contractile cells in its body wall Cnidarians and annelids.

Hydra closes its mouth and the cells encircling its body wall constrict

Elongates and its tentacles extend Mouth opens, allowing water to flow out, and

longitudinal cells in its body wall contract, shortening the body.

Exoskeletons

External skeleton usually made of chitin or calcium carbonate

Many arthropods and most mollusks Jointed exoskeletons allow to swim, fly, burrow,

walk, crawl, and leap May be water tight Offer protection from predators.

Molting Breaking out of their exoskeleton and grow a new one

to allow for growth Relatively heavy especially in large arthropods.

Endoskeletons

Structural support system within the body.

Vertebrates have an endoskeleton made of cartilage or a combination of cartilage and bone Sharks and some other fishes have skeletons made

entirely of cartilage Girdles

Support limbs and allow for movement.

Cannot protect an animal the way that an exoskeleton can

Internal skeleton can grow as an animal grows, so the animal does not need to molt

Lighter weight than exoskeleton.

Joints

Places where parts of a skeleton are held together that allows them to move with respect to one another.

Ligament Connects bones together at

joints Strong connective tissues.

Muscles and Movement

Specialized tissues that produce physical force by contracting when stimulated

Muscles relax when they aren’t stimulated Generate force in only ONE direction.

Muscles are arranged in pairs or groups that pull parts of the skeleton in opposite directions.

Tendon Attaches muscle to bones around

the joints Tough connective tissue.

Exoskeleton Muscles are attached to the inside of the exoskeleton

Endoskeleton Muscles are attached around the outside of bones.

Vertebrate Muscular and Skeletal Systems

The shapes and relative positions of bones, muscles, and joints are linked very closely to the functions they perform Many very different arrangements Many very different kinds of movement.