Lektion 2 - Invertebrates Flashcards
What properties are shared by animals?
- Multicellular
- Collection od “trans-dev” genes
- Hetrotrophs (predators, herbivors, omnivores, detertivores)
- specialized extracellular matrix
-can move (celia or muscles) - nervous system
-Epithelia and mesenchymes - sexual reproduction ;)
what is asymmetry in animals?
No organized body symmetry (ex sponges)
what is radical symmetry in animals?
The body is centered around a midline axis (cnidarians and ctenophores)
- no left/right or atero/posterior axis
- Oral-aboral axis defines
What is Bilateral symmetry in animals?
Plane of symmetry at the midline axis (bilaterians)
What are the basal non-bilaterian animals?
Sponges, cnidarians and ctenophores
do sponges have distinct organs?
no
do sponges have neurons?
no
How do sponges feed?
They are filter feeders
what is ostia?
pores on a sponge that water flows trough
What is the simplest animal?
sponge
Important facts about Cnidarians?
Nässeldjur:
-jellyfish and corals
-radial body plan
- one opening that functions as both mouth and anus
-predatory
what is endoderm, ectoderm and mesoderm?
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer)
Does Cnidarians have ectoderm, endoderm and/or mesoderm layers?
ectoderm, endoderm
What ephithelia does a sponge have?
Edoderm - lining of the gut
Ectoderm - skin
Describe the cnidarian nervous system.
- nerve net (ectodermal and endodermal)
- simple nervous systems
- sensory neurons and ganglion neurons
- simple sensory organs calles rhopalia around the mouth
what are cnidocytes?
cnidocytes discharge a barbed thread that penetrates the prey when stimulated.
they are used for defence and protection
they are the hallmark for cnidarians
Facts about Ctenophores
- swim with celia
-have a through gut
-body plan similar to cnidaria (ex radial body plan)
what is the cambrian explosion?
a time period where there was a sudden explosion in amount of species that occured due to more plants outside of water that caused an explosion in oxygen.
what charachterizes bilateria?
-Their body symmetry (bilateral)
-Mesoderm
- Coelomic cavities
-through gut
What is cephalization?
evolution of a head at the anterior end with concentration of sense organ and enlarged brain
what is the bilaterian body plan?
- tube in a tube
- gut mesoderm
- body wall mesoderm
- coeloms
What are the functions of a coelom?
- get bigger
-distribute fluids with nutrients, waste and hormones - accomodate inner organs
-hydroskeleton
what is the mesoderm?
The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals.
What does it mean for a mesoderm to be schizocoely formed?
1) the mesoderm intercalates between the extoderm and endoderm
2) coeloms form by splitting the mass of mesoderm
Formed this way for protostomes (except flatworms and namatodes)
