A skeletal system supports the body, protects internal organs, and helps an organism move. This lesson introduces the three main skeletal designs and explains how each supports movement in different kinds of animals.
A hydrostatic skeleton is a fluid-filled compartment within the body. In many animals, this compartment is the coelom. The fluid supports internal organs and resists external compression. Muscles surrounding the compartment contract to change its shape; pressure in the fluid then helps produce movement.
All flashcards
What is a hydrostatic skeleton?
A fluid-filled body compartment whose pressure supports organs and works with surrounding muscles to produce movement.
Why do arthropods molt?
Their rigid exoskeleton cannot expand as they grow, so they shed it periodically.
What structures make up the axial skeleton?
The skull, auditory ossicles, hyoid bone, vertebral column, and thoracic cage.
What is the role of intervertebral discs?
They cushion shocks, bind adjacent vertebrae, and allow some spinal movement.
What is the appendicular skeleton?
The limbs and the pectoral and pelvic girdles that attach them to the axial skeleton.
Quiz questions
How does a hydrostatic skeleton help produce movement?Answer: Muscles change the shape of a fluid-filled compartment, and its pressure helps move the body.
Why must many arthropods shed their exoskeleton as they grow?Answer: The acellular covering cannot expand to accommodate a larger body.
How many bones make up the adult vertebral column, and what are they?Answer: Twenty-six: 24 vertebrae, the sacrum, and the coccyx.
Which statement describes the pelvic girdle?Answer: It attaches the lower limbs to the axial skeleton and helps bear body weight.
Why is placing limbs beneath the body advantageous for terrestrial locomotion?Answer: It reduces the force needed to move forward and allows limbs to swing more efficiently.
Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.