Exam 2 Flashcards
Deuterostome development
Eight-cell stage is radial and indeterminate
Folds of archenterpn form coelom
Anus develops from blastopore
Sponge structure
(1) sponges are suspension feeders, capturing food particles suspended in the water that passes through their body
(2) water is drawn through pores into a cavity called the spongocoel and out through an opening called the osculum
(3) sponges consist of a gelatinous noncellular mesohyl layer between 2 cell layers
First step for categorizing animals
Diploblasty vs Triploblasty as developing:
Diploblastic: 2 germ layers:ectoderm (outside), endoderm (inside)
Triploblastic: 3 germ layers: Ectoderm - leads to skin and nervous system, Endoderm - leads to digestive system, Mesoderm (middle) - leads to everything else (circulatory, bone, muscle, etc)
2nd step for categorizing animals
Radial symmetry in adults or Bilateral symmetry:
Radial: 2 planes, usually only in diploblastic organisms, ctenophores, cnidarians
Bilateral symmetry: single plane, anterior side (brain + sensory organs), posterior side (digestive track), dorsal side (top), ventral side (bottom)
Body cavities
Coelomates: tube within a tube, enclosed body cavity completely lined with mesoderm
Acoelomates: no coelom “just a tube”
Pseudocoelomates: enclosed body cavity that is partly lined w/mesoderm
How many living species of animals have scientists identified?
1.8 million
Eukaryotes are
cells with nucleus
- lack cell walls
- heterotrophs: carbon comes from other organisms
- motility
- all except sponges have 2 systems: nerve cells, muscle cells
- basal group is phylum porifera (sponges)
synapomorphy of heterotrophs is
multicellularity
Animilia group includes
Porifera (sponges), Ctenophora (comb jellies), Cnidaria (jellyfish, coral, sea anemones), Acoela, Rotifera (rotifers), Platyhelminthes (flatworms), Annelida (segmented worms), Mollusca (snails, clams, squid), Nematoda (roundworms), Arthropoda (insects, spiders, crustaceans), Echinodermata (sea stars, sand dollars), chordata (vertebrates, tunicates)
Protostome group includes
Rotifera, Platyhelminthes, Annelida, Nematoda, Arthropoda
Deuterostome group includes
Echinodermata, Chordata
Deuterostome group includes
Echinodermata, Chordata
Choanoflagellates vs Sponges
Individual choanoflagellate is a single cell
Sponges have collar cells (choanocytes) - the tail makes a current to give oxygen to cell, but multicellular so many cell types
Animal body plans vary according to
organization of the animal’s tissues
Tissues are
collections of specialized cells isolated from other tissues by membranous layers
During development, three germ layers give rise to
the tissues and organs of the animal embryo
Radial symmetry occurs in mostly ______ organisms
sessile or planktonic
Sessile organisms
organisms anchored to the benthic environment (to the bottom of the ocean)
Bilateral symmetry allows organisms to
move actively
The Diploblastic organisms are
Ctenophores and Cnidarians
The triploblastic organisms are
Acoela, Rotifers, Platyhelminthes, Annelids, Mollusca, Nematodes, Arthropods, Echinoderms, Chordates
The zygote of an animal undergoes a series of mitotic cell divisions called
cleavage
An 8-cell embryo is formed by ____ rounds of cell division
3
Blastula
In most animals, cleavage produces a multicellular stage called a blastula. The blastula is typically a hollow ball of cells that surround a cavity called blastocoel (innermost empty space)