SI Lectures 20,21,22 Flashcards
Choanoflagellates
are the closest (unicellular) protist
relatives of animals and resemble the COLLAR CELLS of sponges
called CHOANOCYTES
What three characteristics do all animals share?
- Heterotrophic (consumers)
- Multicellular (lack cell walls)
- Tissues that develop from embryonic layers
- Ectoderm, endoderm, and mesoderm
Protostome
- Spiral (diagonal) and Determinate cleavage (fate is set) at 8 cell stage
- Solid masses of mesoderm form
coelom - Mouth develops from blastopore
Deuterostome
- Radial (parallel or perp) + indeterminate
cleavage at 8 cell stage - Folds of archenteron form coelom
- Anus develops from blastopore
What is the current hypothesis of animal phylogeny mainly based on?
Molecular data – nucleotide sequences of small subunit ribosomal RNA
Porifera (sponges)
Major Characteristic:
Metazoa (oldest extant phyla)
(monophyletic)
(ok to note that some web-sources counter the book to say that sponges are not metazoa. We will follow out text on this one)
Symmetry and Coelom Presence:
- asymmetrical
- lack tissues
Anatomy Fact:
Spicules (found in most sponges to provide structural support and deter predators – can be used for identification)
ETC:
MOST basal animals
Cnidaria
Major Characteristic:
Eumetazoa
Symmetry and Coelom Presence:
Radial symmetry; diploblastic (lacks coelom; (has mesoglea instead of mesoderm)
Anatomy Fact:
- Polyp (tentacles up and free swimming); -
- medusa (tentacles stuck to ground)
- Cnidocytes grab prey (produce nematocysts with toxins)
ETC:
- Digestive compartment = gastrovascular cavity (single opening functions as mouth and anus)
- multiple rhopalia for sense organs
Ctenophora
Major Characteristic:
Eumetazoan
Symmetry and Coelom Presence:
- Biradial + radial symmetry
- diploblastic ( lacks coelom)
Anatomy Fact:
- fused cilia called ctenes used for locomotion
- tentacles have colloblasts (sticky cells) for prey capture
ETC:
- apical sense organ (statocyst)= controls comb rows
- single opening functions as mouth and anus
Hemichordata
Major Characteristic:
Deuterostomia
Symmetry and Coelom Presence:
few things in common with chordates = gill slits and dorsal nerve cord
Anatomy Fact:
ETC:
acorn worm
Echinodermata
Major Characteristic:
Deuterostomia
Symmetry and Coelom Presence:
- Bilateral Larvae
- coelomates
Anatomy Fact:
- Water vascular system,
- 5-part symmetry,
- tube feet (how they move up and down)
ETC:
Chordata
Platyhelminthes (flatworms)
Major Characteristic:
Lophotrochozoa
Symmetry and Coelom Presence:
- bilateral
- acoelomate
Anatomy Fact:
- Free living = gastrovascular cavity
- Parasites = absorbs from host
ETC:
parasite called tapeworm
Rotifera
Major Characteristic:
Lophotrochozoa
Symmetry and Coelom Presence:
- bilateral
- pseudocoelomate
Anatomy Fact:
- Alimentary canal (mouth + anus)
- Cilia crown brings water in, grinds food
against trophi
ETC:
Lophophorate
(ectoprocts and brachiopods)
Major Characteristic:
Lophotrochozoa
Symmetry and Coelom Presence:
- bilateral
- coelomates
Anatomy Fact:
Lophophores = Ciliated tentacles bring food in
ETC:
Mollusca
Major Characteristic:
Lophotrochozoa
Symmetry and Coelom Presence:
- bilateral
- coelomates
Anatomy Fact:
radula= rasp like organ
ETC:
- Contains muscular foot
- visceral mass (w/ organs)
-mantle which secretes calcium carb shell
