lab practical II

Explain how cnidocytes with their nematocyst function in food capture and defense.

the nematocysts in cnidocytes shoot their barbed stinging filament to capture prey. stinging aids in subduing its prey and their filaments to help get a firm hold. they can also use this as a defense mechanism

the complete digestive tract of nematodes and other phyla allows functional specialization. what specializations are common in the digestive tract of higher organisms such as humans?

the stomach, teeth, and liver are the common specializations

mollusks exhibit a variety of feeding methods. list at least 4 and discuss adaptations and examples for each type.

they can be carnivores that hunt other prey, herbivores that scratch the surface of plants, suspension feeders, grazing herbivores, and carnivores that capture small organisms with their tentacles

cephalopods are considered by many to be the most distinctive calls of mollusks. what makes them seem almost out of place?

they have more developed CV systems and nervous systems, arms tentacles, ink sacks, chromatapore, and jet propulsion

of what economic importance are earthworms?

they have they ability to improve fertile soil in different ways which is why they are very important in the world of agriculture

why are spicules used as a primary characteristic to classify sponges?

because spicule shape and prong numbers vary amongst different types of sponges

why are sponges considered an evolutionary dead end?

because sponges specialize in pumping water through their bodies so well its impossible to modify, and change their bodies to move towards water that is rich in food and nutrients

which group within kingdom Protista probably gave rise to sponges?

choanoflagellates

what are the disadvantages of a flatworm's digestive system having only one opening?

it cannot consume food continuously

flatworms are the first organisms we have discussed with an anterior-posterior orientation. How does this affect their movement compared to the movement of more primitive organisms?

it has more coordinated and deliberate movement having the orientation of anterior-posterior allows to move towards and away from food and predators

define ectoparasites

a parasite, such as a flea, that lives on the outside of its host

Define endoparasite

a parasite, such as tapeworm, that lives inside its host

What is extra cellular digestion?

a process in which saprobionts feed by secreting enzymes through the cell membrane onto the food. the enzymes catalyze digestion of the food into molecules small enough to be taken up by passive diffusion, transport, or phagocytosis

Define sessile

fixed in one place; immobile

what is the advantage of radial symmetry for sessile animals such as hydras and bilateral symmetry for mobile animals such as planaria? what major evolutionary trends accompany bilateral symmetry?

radical symmetry is useful for sessile animals because of the fact they have the ability to sit and grab food or see threats from multiple different directions. bilateral symmetry is useful for motile animals and cephalization accompanies bilateral symmetry