M1: L4: Porifera (Sponges), Cnidaria

What arose around 700 MYA?

first animals (suggested by evidence)

What dated back to 560 MYA?

first fossilized animal remains

What period contained a diversification of animal taxa?

Ediacaran

What period contain an explosion of classes of animals?

Cambrian

What are the 3 factors that contributed to the Cambrian explosion?

1) evidence for most the animal phyla

2) explosion due to predator-prey interactions 

3) increase in O₂ and evo of Hox genes

During the Cambrain Explosion, what type of vertabrates were most of the animal phyla?

invertabrates, except one

During the Cambrian Explosion, what lead to rapid diversification and evo of bilateria?

predator-prey interactions

Why is sponges called phylum porifera?

covered in a bunch of pores

What are the characteristics of the phylum porifera?

1) no true tissue

a) have specialized cells that perform diff func

2) mobile in larval stage // adults are sessile (immobile)

3) filter feeders

4) asymmetry

What are the 3 specialized cells of the phylum porifera (sponges)?

1) epidermis: thin protective layer

2) choanocyte/colllar cells: inner lining

3) amoebocyte: mobile support cells

What is the func of the ostium (pores)?

allows water to flow in

What is the func of the choanocytes (collar cells)?

uses their flagellum to brings the water in

What is the func of osculum?

allows water to flow out

What is the func of the amoebocyte?

feed on the small food particles

How does the phylum porifera prevents filtering the same water over and over again?

1) oscula has a lower cross-sectional area than the ostia

2) fewer oscula than ostia

3) the smaller space of the oscula forces the acceleration of the water and flinging father from the sponge

What are the amoebocytes? What are their function?

support cells —

1) move within the matric btwn the 2 layers of cells

2) secret material (spicules or spongin) to make the sponge’s skeleton

3) totipotent 

totipotent means they can turn into other cell types

What specific substances do the amoebocytes secretes?

spicules — calcium carbonate or silica

spongin — softer protein

What animal phyla is the most basal in the metazoa?

p porifera (sponges)

What are the characteristics of the phylum cnidaria?

1) have tissues

a) diploblastic: 2 tissue layers

2) radial symmetry

3) sessile forms (polyps) // mobile forms (medusa)

What organisms are part of the phylum cnidaria?

medusozoa — jellies, boc jellies, hydrazoans (like hydra)

anthozoa — anemones and corals — polyps only

What do we know about the phylum cnidaria from the cladogram?

1) taxon split off ~ 680 MYA

2) branched into 2 clades: medusozoa and anthozoa

antho- means flower

-zoa means animals

What is the relationship btwn the corals and the zozan?

???

What are the specific characteristics in Cnidaria?

1) have muscles (contractile fibers)

2) have nerves

a) forms a nerve net

b) no brain — responses to stimulli

3) have more complex sensory organs (ex: ocelli (eye spots))

What are “Box Jellies”?

have eyes that are better than the simple ocelli of other jellies

What types of production happen on the medua?

asexual reproduction

What is the life cycle of the medusa?

medusa: feeding form — planula larva — polyp — budding polyp — ephyra — medusa (again)

What is the life cycle of the hydrozoans?

obelia:

colony contains feeding polyps and medusa polyps — medusa w sperm and eggs — zygotes — swmming planula — states new colony by asex. reprod.

What are the diploblastic layers?

gastrovascular cavity: food digestive chamber

lined by the gastrodermis

epidermis 

mesoglea contains cells, not fluids // lined btwn the epidermis and gastrodermis

tentacles contains nematocyst —  func? passively predatory

Wath are nematocysts?

neurotoxins — causes immobilization in animals