sponges

Phylum Porifera (sponges)

Play important ecological roles
Water quality (filter feeding)
Habitat (home for other species)

Most unique cell in sponges

choanocytes

Choanocytes

Capture of food

How do choanocytes capture food

Flagellum moves water, collar retains food particles (filter feeding)

Amoebocyte

Digestion of food particles

What forms the "skeleton"

Spicules (like bones)

Sclerocyte

Cell that secretes spicules

Pinacocytes

T shaped epithelial cell

Porocyte

Water flow regulation cell

Archaeocytes/Amoebocytes

Digestion and absorption

Asexual of porifera (2 ways)

Fragmentation
Gemmulas

Fragmentation

Portion of sponge detaches and builds a new one

Gemmulas

"Seeds" filled with amoebocyctes that are sealed during hard conditions and released once conditions improve

Sponges are hermaphrodites

Produce both gametes at same time

Porifera sperms derived from

Choanocytes

Porifera oocytes derived from

Archaeocytes

Porifera fertilization

External or internal

External fertilization

Sperms and oocytes are released into the water column

Internal fertilization

Sperms released in water are caught by another sponge and moved into mesoglea where oocytes are waiting

What stage is very important for sessile species

Dispersal stage

Dispersal stage

After drifting, the larva will settle and form a new sponge

3 classes of Porifera

Calcarea, Hexactinellida, Demospongiae

Class calcarea

3 ray calcarean spicules
Mainly shallow water

Class Hexactinellida

Glassy sponges with 6 ray siliceous spicules
Deep sea

Class Demospongiae

Siliceous spicules + collagen
Leucon (rounds

3 Types of Symmetry

Spherical, radial, bilateral

Spherical symmetry

Typical of many protozoans (not animals)
Infinite planes

Radial symmetry

Mainly cnidarians and ctenophores
2+ planes

Bilateral

Left and right divided by one plane

Cnidarians

Radial symmetry
Developed tissues
Basic organs
Diploblastic

Diploblastic

Two germ layers and mesoglea

Two body types of cnidarians

polyp and medusa

Polyp

Fixed to ground
Mouth up

Medusa

Mobile
Mouth down

Gastrovascular cavity

Where extracellular digestion takes place
(Simple digestion system)

Endoderm

Layer of cell lining the gastrovascular cavity

What does endoderm have

Gland and nutritive cells

Mesoglea

Matrix with cells and fibres
More prominent in Medusa

Role of mesoglea

Provides shape and help to float/ drift

In the polyp, the mesoglea is

Thin and not as important

Ectoderm

Epidermis with a net of sensory cells (ocelli, statocysts) around the bell or umbrella

Unique cell to cnidarians

Cnidocyte

Cnidocyte

Unique cells with harpoon like structure called nematocysts

Nematocysts

Hunting

Classification of cnidarians

Hydrozoa, Scyphozoa, Anthozoa

Hydrozoa

Both medusa and polyp are important

Scyphozoa

medusa dominant

Anthozoa

Polyp only