Lecture 15 - Animals Flashcards
Describe the kingdom Animalia
(also known as Metazoa)
- > multicellular, heterotrophic eukaryotes (ingest and digest)
- > lack cell walls; rely on proteins external to cell membrane for support and cell connection (i.e. collagen)
- > most capable of complex and (relatively) rapid movements
Major evolutionary changes of animalia
what makes Porifera (sponges) animals and not protists
the specialization of cells
Eumetazoa
group of metazoa (animals) excluding sponges due the the development of tissue/groups of cells with a common function
- > specifically muscle and nerve tissue
- > sponges are excluded because they don’t have either
how do Eumetazoa organisms develop
they are developed through…
- Cleavage
- > mitotic cell divisions without cell growth, typically results in blastula (multicellular hollow balls) - Gastrulation
- > layers of embryonic germ tissues that form tissues and organs are produced
Diploblastic eumetazoa
Eumetazoa with two germ layers
1. Ectoderm (outer)
- > outer covering (dermis)
- > in some groups the central nervous tissue
2. Endoderm (inner)
- > lining of the digestive tract
- > in some groups organs such as liver, lungs etc.
Radial symmetry
when you can cut an organism in 2 equal half from any direction
single opening
when an organisms mouth/anus on dorsal surface
two forms of Cnidarians and Ctenophores
(both eumetazoa diploblasts)
Polyp: attached form that waits for prey; attached to a surface
Medusa: moves in water to catch prey
Bilateria
subclass of eumetazoa that exibit bilateral symmetry
BS - > can only cut an organism in half 1 way to get 2 equal halfs
- > typically motile and develop sensory tissues at anterior and including concentration of nervous tissue (brain - cephalization)
Triploblastic Bilateria
triploblastic = 3 germs cells, including mesoderm
- > produces muscles and most organs between dermis and digestive tracts
- > often forms coelom between dermis and digestive tract
Two modes of early Bilateria development
Protostome
- > spiral and determinate - division diagonal to vertical axis and fate is cast very early
- > mesoderm cells split to form coelom
- > blastopore becomes mouth
Deuterostome
- > radial and indeterminate- division parallel or perpendicular to vertical axis and fate is cast late
- > coelom forms as the mesoderm grows an folds outward
- > blastopore becomes anus
reproduction of animals
Asexual reproduction
- > Asexual reproduction occurs if a few groups through budding and parthenogenesis
Sexual reproduction
- > sexual cycle typically diplontic with oogamy
- > zygote undergoes set developmental pattern with tissues produced from embryonic germ layers
Cnidarian life cycle
how long ago did THE ancestral animal diverge
800-675 million years ago
