Biology 11

25.1 FlatwormsBody Structure of Flatworms

Flatworms are on the _________________ branch of the evolutionary tree. ________________ symmetry Thin, _________ bodies Definite __________ region and body ______________ Lack a ____________

Feeding and Digestion Free-living flatworms feed on __________ or ___________________ organisms. ______________ flatworms have modified feeding structures called __________ and

______________, which enable them to stay _____________ to their hosts.

Respiration, Circulation, and Excretion _______________ moves dissolved ___________ and ______________ to all parts of

their bodies. _______________ _____________ and other ____________ also are removed from

flatworm cells by diffusion. ____________ cells move water out of the body to excrete waste products and maintain

____________ _____________.

Response to Stimuli The __________ system regulates the body’s response to

stimuli.

Movement Move by ____________ muscles in the body __________ Glide by using __________ located on their undersides

Reproduction Flatworms are ________________. Two different flatworms exchange _________, and the _______ are fertilized internally. ______________ flatworms can reproduce asexually by __________________.

Biology 11

Turbellarians Live in ___________ or freshwater Have _____________ that can detect the

presence or absence of __________ Sensory cells help them identify chemicals and

water movement.

Trematodes Parasites that infect the _________ or body

___________ of their hosts The parasitic fluke Schistosoma requires ________ hosts to complete its life cycle. These fluke eggs clog blood vessels, causing swelling and eventual tissue damage.

Cestodes Parasites adapted to life in the _____________ of their hosts ________________ form continuously; as new ones form near the __________, older

proglottids move farther back and mature.