Animal Diversity Flashcards
What are some common characteristics of animals?
They eukaryotic, multicellular, heterotrophic organisms with cells specialized to perform specific functions. Most animals are capable of locomotion at some time during their life cycle, can respond adaptively to external stimuli, and can reproduce sexually.
How does the life cycle usually occur in most animals?
In sexual reproduction, sperm and eggs unite to form a zygote. The zygote undergoes cleavage, which produces a blastula. Most animals develop into a larva that usually goes through metamorphosis.
What are the advantages of life in the ocean?
Marine environments have stable temperatures, provide buoyancy, and provide readily available food. Fluid and salt are better maintained.
What are the disadvantages of life in the ocean?
Currents and other water movements
What are the advantages of life in fresh water?
Because fresh water is hypotonic to tissue fluid, animals must osmoregulate (removing excess water but retaining salts).
What are the disadvantages of life in fresh water?
It offers less constant environment and less food.
What are the advantages of life on land?
Adaptations that protect them from drying out and temperature changes, and protect their gametes and embryos.
What are the disadvantages of life on land?
Dessication (drying out) and temperature changes
What hypothesis traces the early evolution of animals?
Based on molecular data, most animals clades diverged over a long period during the Proterozoic eon. During the Cambrian radiation, new animal body plans rapidly evolved among the clades.
How does the number of tissue layers infer relationships between animal phyla?
Embryonic tissues are also called germ layers, which has three layers: ectoderm (outer), endoderm (inner), and mesoderm (middle).
What is the ectoderm layer?
It gives rise to the body covering and the nervous system.
What is the endoderm layer?
It lines the gut and other digestive organs.
What is the mesoderm?
It gives rise to muscle, skeletal structures, and most other body structures.
How does the type of body cavity infer relationships between animal phyla?
Acoelomate animals have no body cavity. Coelomate animals have a true coelom (lined with the mesoderm). Pseudocoelom animals have a false body cavity that is not aligned with the mesoderm.
What are the two branches of bilateral animals?
Protostomia and Deuterostomia
