M1: L4: Porifera (Sponges), Cnidaria

What is the origins of animals? In other words, when did the first animals first arise?

metazoa arise ~ 700 MYA

How old is the first direct evidence of life?

3.5 BYA

Though confirmed eukaryotic fossils go back about 1.8 BYA, molecular data suggests the earliest eukaryotes probably appeared more than ____ BYA.

2 BYA

Our oldest known fossils of multicellularity currently date back how many years?

1.3 BYA

Why do you think the Cambrian Explosion got the 2nd part of its name?

a burst of animal phyla and marine species (algae and fish) evolution

What are the 2 factors that contributed to the Cambrian explosion?

1) predator-prey interactions 

2) increase in O₂ and evo of Hox genes

Name the 4 eras from oldest to earliest.

Precambrian, Paleozoic, Mesozoic, and Cenozoic

What organism(s) were present during the precambian era?

animals

What organism(s) were present during the paleozoic era?

fish

What organism(s) were present during the mesozoic era?

dinosaurs

What organism(s) were present during the cenozoic era?

genus homo

What are the characteristics of the phylum porifera?

1) no true tissue

2) specialized cells (epidermal, choanocytes, and amoebocytes)

3) mobile larvae // sessile adults

4) filter feeders

5) asymmetry

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

1) epidermis: protective outer layer

2) choanocyte/colllar cells: inner lining

3) amoebocyte: mobile support cells

What is the func of the ostium/ostia (small pores)?

allows water to flow in

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

1) collar of filaments covered in mucus — traps food particles

2) flagellum flaps/beats — pulls water in

What is the func of osculum/oscula?

allows water to flow out

What is the func of the amoebocyte?

1) structural support

2) totipotent

3) secrete skeleton material (spicules/spongin)

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

1) oscula/osculum 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 specific substances do the amoebocytes secretes?

spicules — calcium carbonate or silica — hard

spongin protein — soft

What animal phyla is the most basal in the metazoa?

p porifera (sponges)

What are the characteristics of the phylum cnidaria?

1) have tissues (eumetazoa): muscles and nerves

a) diploblastic: 2 tissue layers

2) radial symmetry

3) two body forms:

a) sessile forms (polyps)

b) mobile forms (medusa)

What are the 2 major clades and the organisms part of the phylum cnidaria?

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

anthozoa — anemones and corals — polyps only

What is the nervous system of the Cnidaria?

a) forms a nerve net

b) no brain — responses to stimulli

c) some jellies have more complex sensory organs (ex: ocelli (eye spots))

What adaptation makes “Box Jellies” more advanced than typical cnidarians?

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

What types of production happen on the medusa to the planula larva?

sexual reproduction

What is the life cycle of the medusa?

sexual reprod: medusa — planula larva —  asexual reprod: polyp — budding polyp — ephyra — medusa (again)

What do the cnidarians use for feeding and defending themselves?

tentacles w nematocysts

What is the life cycle of the hydrozoans?

colony: feeding polyps and medusa polyps — medusa w sperm and medusa w eggs — zygotes — blastula — swimming planula — planula — new colony by asex. reprod.

What are the structure of the polyp and medusa? What are the two tissue layers (bolded)?

1) gastrovascular cavity: incomplete sack-like gut

2) gastrodermis lines the GVC

3) mesoglea: gelatinous-like fluids

4) epidermis 

5) tentacles

6) mouth/anus

What are nematocysts?

a type of cnidocytes that contain neurotoxins — causes immobilization or paralyzation in animals

How does water flow into the p porifera?

1) enters thru the ostia

2) enters the spongocoel

3) exits out the osculum

give an example of an organism of the hydrozoans.

portuguese man of war