Topic 2: Animal Diversity pt 1 Flashcards
(73 cards)
What are the 3 ways animals can be differentiated from plants and fungi?
- Nutritional mode: animals are heterotrophs that feed via ingestion 2. cell structure and specialization: animals are eukaryotic and mostly multicellular. They lack cell walls. Contain collagen. Specialized cells are organized into tissues (have muscle and nerve tissues). 3. Reproduction and development: mostly sexual, dominated by a diplontic life cycle (2N), only gametes haploid.
in animal development some animals (larvae) undergo
metamorphosis
much of animal form is controlled by
homeoboxes (which contain family of genes called: Hox genes)
define cleavage
a series of mitotic divisions
describe the steps of cleavage
After 3 divisions an eight-celled embryo is formed. Eventually a blastula is produced: a hallow ball of cells that surround a cavity called the blastocoel. Then Gastrulation occurs, folding one end of the embryo inward, expanding into the blastocoel. This produces layers of tissues: the ectoderm (outermost layer), & the endoderm (innermost). Then the archenteron (pouch formed by gastrulation opens to the outside via the blastopore. Which will develop into the end of the digestive tract. The endoderm (of the archenteron) then develops into the digestive tract.
what’s a body plan and what are some features that a body plan includes?
morphological and developmental traits integrated into a whole being. Includes: symmetry, tissues, and body cavities.
describe the types of symmetry
asymmetry: lack symmetry, radial symmetry: (circular), no sides or front/back, can be cut in half evenly many ways, often sessile organisms. Bilateral symmetry: two-sided symmetry, can only be cut in half evenly one way, often mobile organisms.
most bilateral animals have what, and describe it
cephalization (concentration of sensory organs and nerves, a brain)
What is the only animal that lacks tissues? What clade of their own are they in because they don’t have true tissues? what clade are other animals in that don’t have true tissues?
Sponges, they are in Parazoa, and other animals are in Eumetazoa.
Most animals have tissues (germ layers) because of gastrulation, describe the 3 layers
ectoderm: covers surface, mesoderm: fills the space between ecto- and endoderms, forming muscles and other organs, Endoderm: forms digestive tract
different animals have different numbers of germ layers what are the 2 variations and examples of each
diploblastic: two germ layers ex: Cnidarians. Triploblastic: 3 germ layers ex: all bilateral animals
body cavities
fluid filled spaces between the digestive tract and outer body wall
many triploblastic animals have what? what is it derived from
coelom, it is derived from the mesoderm.
what is the function of the coelom?
it cushions internal organs and acts as a skeleton in some worms.
Hemocoel
a body cavity that some triploblastic animals have, it is involved in internal circulation, nutrient transport, and hydrostatic skeletons. The fluid that is circulated is the hemolymph. (so all animals with an open circulatory system have a hemocoel)
whats an animal with both a coelom and hemocoel called?
A eucoelmate
what’s an animal with only a hemocoel called?
a pseudocoelomate (false coelom)
what’s an animal with neither coelom or hemocoel?
an acoelomate
Explain the 2 developmental modes (cleavage types, and mesoderm and blastopore fate)
- Protostome development: undergo spiral cleavage, and determinate cleavage (cell fates are determined early on). Solid mass of mesoderm splits to form the coelom, and the blastopore becomes the mouth (second opening becomes anus p=primary mouth 1st).
- Deuterostome development: undergo radial cleavage, and indeterminate cleavage (each cell retains the capacity to, in isolation, develop into a complete embryo). The mesoderm buds from the wall of the archenteron, and the cavity produced from the budding becomes the coelom, the blastopore becomes the anus, (second opening becomes mouth)
what was the common ancestor of all animals
a choanoflagellate
what clade are all animals in
metazoa
what animal branches off first (basal animal), what phylum and clade is this animal?
Sponges, phylum porifera, clade parazoa
what clade are all animals except sponges in because they have true tissues?
eumetazoa
what are the only phyla that are in the clade radiata and diploblastic
Ctenophora, and cnidaria