Chapter 23 & 24 Flashcards
Where does the name cnidarian mean? Give three characteristics of this group.
Cnidarian means stinging nettle plant.
- radially symmetric
- two layered body
- Medusae and polyp life style
How do Cnidarians obtain their food?
Their stinging cells help to capture prey.
Jellyfish lack circulatory, excretory, and support structures. Why are these organs not necessary? What limitation does this place on their habitat?
Each cell is in contact with the water and can diffuse material directly in and out of the cell. They are restricted to a water habitat.
Most Cnidarians alternate between a Medusa and polyp stage. What is a disadvantage and an advantage of the polyp stage? How does this compare to sponge life cycle?
Polyp Disadvantage- can not disperse, can not move to find food or escape an unfavorable environment.
Advantage- does not expend energy on moving.
Both sponges and jelly fish have a sessile and mobile stage.
The polyp reproduces asexually and the Medusa reproduces sexually. What are the advantages and disadvantages sexual and asexual reproduction?
Sexual reproduction is not as efficient as asexual reproduction. Sexual reproduction adds and maintains variability in a species and increases the chance of survival of some offspring in a changing environment.
Both sponges (Porifera) and Cnidarians lack of Brian. What is the disadvantage of lacking a brain?
There will be no memory, learning, decisions, etc.
What can we say about the habitat of Cnidarians?
Cnidarians are restricted to water and are largely dependent upon water currents.
Give four adaptations that the has tapeworms for a parasite life?
Multiple hosts, sexual and asexual reproduction, a scolex with hooks, lack a gastrovascular system
Describe the life cycle of a the beef tapeworm
Cow, cyst in muscle, humans eat the muscle, human’s intestine, egg, cow eats egg
Describe the life cycle of the pig tapeworm.
Tapeworm lives in the human intestine, egg, pig eats egg, tapeworm forms a cyst in the pig muscle, humans eat the pig muscle.
How do humans acquire the pig tapeworms and what can be done to prevent infection?
Eating the pig muscle. It can be avoided by thoroughly cooking the muscle.
How do pigs acquire the tape worm and how can that be avoided?
Pig infection can be avoided by the proper treatment of human waste.
Give four functions of the mantle in a mollusk
Respiratory chamber, in bivalves it aids in feeding, in some mollusks it serves as a brood chamber, and can aid in locomotion
How does a shell extend the habitat of a snail?
Provides protection and prevents water loss
A clam shell limits the ability of a clam to find a mate and disperse. How are these problems solved? What is a trochophore larvae?
Gametes are released into the water allowing for dispersion and the trochophore larvae is free swimming.
The characteristics of echinoderms are interlocking what symmetry as an adult.
Spines, radial
What do starfish eat and how do they eat?
They eat bivalve mollusks by forcing its stick into the bivalve shell and externally digesting the clam.
Speculate what would happen if starfish were eliminated from an ecosystem.
The clams would become too numerous and reduce their food source.
Starfish are called a keystone species. What is a keystone species and why are starfish called a keystone species?
A keystone species is a species which critical for the preservation of the ecosystem. If starfish are removed the clams will over populate.
Speculate what would happen if all mosquitoes were eliminated?
Mosquitoes are a food source for many animals, and they are important pollinators. Without mosquitoes the ecosystem would probably continue; however, there would be a relative change in species composition.
