Introduction to Animal Bodies Flashcards
What key animal characteristics make them such efficient consumers?
-heterotrophic
-tissues formed from layers of embryonic cells
-efficient digestive system
-nerve and muscle cells
-can move, detect, and capture potential prey
What do animal cells have instead of cell walls?
Support from structural proteins such as collagen
What type of division produces sperm and egg cells in animals?
Meiotic
Is the animal life cycle dominated by haploid or diploid stage?
Diploid
Cleavage
A succession of cell division without growth between divisions that occurs in animal zygotes
What does cleavage lead to?
The formation of a blastula that will undergo gastrulation
Gastrulation
When a blastula undergoes gastrulation, it forms a gastrula with different layers of embryonic tissues
Larva
Sexually immature, and morphologically and behaviorally distinct from the adult stage
What happens after metamorphosis?
Larvae become juvenile that resemble adults but are sexually immature
What are Hox genes?
Regulatory genes that control the expression of lots of other genes influencing morphology (where eyes should go, etc)
What is believed to be the closest living relatives to animals?
Protists called choanoflagellates; the common ancestor may have resembled modern choanoflagellates
Bilaterian
Organisms with:
-bilaterally symmetric form
-complete digestive tract
-efficient digestive system with a mouth and an anus at opposite ends
What animals were the first to adapt to life on land?
Arthropods; began influencing plants
What two groups of early land vertebrates live today?
Amphibians and amniotes
What happened to reptiles during animal evolution?
Some returned to aquatic habitats, while others remained on land and became adapted for flight
How do radially symmetrical and bilateral animals move?
Radially symmetrical: sessile/planktonic; drifting or weakly swimming
Bilateral: actively move and have a CNS
What is the morphology of a bilaterally symmetrical animal like?
They have a dorsal (top) side and a ventral (bottom) side, a right and left side, a head end and tail end.
Many have sensory equipment (like a brain) in their anterior end
What are the four main types of animal tissues?
Connective, epithelial, muscle, and nervous
What animal(s) lack tissues?
Sponges and a few other groups
What are the two germ layers that give rise to tissues and organs of embryo?
Ectoderm and endoderm
Ectoderm
Covers the embryo’s surface and gives rise to exoskeleton and CNS
Endoderm
Innermost layer, will form the gut and gives rise to the lining of organs and digestive tract
What’s the difference between diploblastic and triploblastic animals?
Diploblastic animals only have ectoderm and endoderm, while triploblastic have a third germ layer called mesoderm
Triploblastic animals
Include all bilaterally symmetrical animals
Mesoderm
Fills space between ectoderm and endoderm, gives rise to muscles and most organs
Body Cavity
Most triploblastic animals have one
fluid- or air-filled space b/w digestive tract and outer body wall
What are the functions of a body cavity?
-Internal fluid cushions suspended organs
-Enables internal organs to grow and move independently of the outer body wall
-acts as a skeleton the muscles of soft-bodied animals can work against
What are the two types of body cavities?
Hemocoel and coelom
Hemocoel
Body cavity formed between mesoderm and endoderm; filled with hemolymph that transports nutrients and waste through body cavity
Coelom
Body cavity surrounded by tissues derived from mesoderm
What are the two developmental modes?
Protostome development and deuterostome development
What types of cleavage are prominent in protostome development?
Spiral cleavage and determinate cleavage
Spiral Cleavage
Planes of cell division are diagonal to the vertical axis of embryo
Determinate Cleavage
Rigidly determines developmental fate of each embryonic cell very early
What types of cleavage are found in deuterostome development?
Radial cleavage and indeterminate cleavage
Radial Cleavage
Planes of division are either parallel or perpendicular to the embryo’s vertical axis
Indeterminate Cleavage
Each cell produced by early cleavage is able to form a complete embryo
Archenteron
Blind pouch formed during gastrulation that becomes the gut
Blastopore
Indentation in gastrula that leads to the formation of the archenteron
What does the blastopore form in the different developments?
Protostome: blastula becomes mouth
Deuterostome: blastula becomes anus
How is coelom formed in the different developments?
Protostome: solid masses of mesoderm split and form coelom
Deuterostome: folds of archenteron form coelom
What data sources are used to infer evolutionary relationships between animal phyla?
Whole genomes, morphological traits, ribosomal RNA (rRNA) genes, Hox genes, protein-coding nuclear genes, and mitochondrial genes
What is the sister group to all other animals?
Sponges
Eumetazoa
Clade of animals with tissues; means “true animals”, includes all except for sponges and a few others
Bilateria Clade
Most animal phyla belong here; most bilaterians are invertebrates, and Chordata is the only phylum that also includes vertebrates
What three clades are bilaterians divided into?
Deuterostomia, Ecdysozoa, and Lophotrochozoa
Deuterostomia
May be invertebrates or vertebrates; includes hemichordates, echinoderms, and chordates
Hemichordates
Acorn worms
Echinoderms
Sea stars and relatives
What do ecdysozoans and lophotrochozoans have in common?
They are all invertebrates
What bilaterian clade do nematodes and arthropods belong to?
Ecdysozoans
What’s special about ecdysozoans?
They secrete an exoskeleton that is shed to allow for growth (process called ecdysis)
What two different features are observed in Lophotrochozoa?
Development of lophophore or developmental stage called trochophore larva
Lophophore
Crown of ciliated tentacles used for feeding
