phylum porifera by chesapeake college

8/9/2019 Phylum Porifera by Chesapeake College

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Phylum Porifera: Sponges

Phylum Porifera: SpongesThe most primitive form of animal life:

No tissues

No mobility

No ability to sense the environment

http://www.oceanarium.com.au/images/red_tree_sponge.gif

Primitive, but successful:

5000+ species

In all oceans, and fresh water Fossils 570MYA (and earlier?)


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No tissues: cellular grade of organization

Filter-feeders

Sessile (=not mobile)

Often vividly colored

http://www.westworld.com/~fabio/gallery/bonaire-scuba-photo/bonaire-purple-tu


Cellular grade of organization:

all functions carried out at the

cellular level.

Diagnostic cell type:

choanocyte: a flagellated cell

with a collar of microvilli


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Choanocyte structure

Flagellum

Cell body

Collar

(microvilli:

extensions of

the cell

membrane)

Choanocyte functionFlagellum

Cell body

Collar

catches food

particles from

water (0.1

m

to 50m)

moves water

through the

collar

ingests food via

phagocytosis

and passes it to

archaeocytes

for digestion

High water flow

also serves

respiratory and

excretory needs


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Choanocytes in situ

Archaeocytes:

amoeboid cells

(totipotent)

Sponge structurespicules (not a cell):

calcium carbonate or

silicon dioxide spines,

for defense & structure

porocyte: barrel-

shaped cell

pinacocyte: flattened

cell on exterior ofsponge

mesohyl: the

acellular goo

between cells


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Spicules: CaCO3 or SiO2

Spongin:

a protein


Other cell types:

Archaeocytes: a general name for amoeboid cells

that carry out:

digestion (and phagocytosis)

spongocytes: secrete spongin

sclerocytes: secrete spicules

collencytes: secrete collagen (a protein)

lophocytes: secrete lotsof collagen

Archaeocytes are totipotent: they can become

any other type of cell in the sponge


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Sponge body plans

Simplest form: ASCONOID(not a taxonomic name):

small, with pinacocytes on

the outside and

choanocytes on the inside;

single chamber

water flow: IN

through an ostium

(=hole in porocyte),into spongocoel, OUT

via osculum

Sponge body plansMore complex form:

SYCONOID (not a taxon):

larger; looks like multiple

asconoid sponges stacked

together

water flow:

IN through an ostium,

into an incurrent canal,

through a prosopyle,

into a radial canal,through an apopyle,

into spongocoel,

OUT via osculum

Fig. 12-5, p. 238


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Syconoid body plan

water flow:

IN through an ostium, into an incurrent canal, through a

prosopyle, into a radial canal, through an apopyle, into

spongocoel, OUT via osculum

Sponge body plansMost complex form: LEUCONOID (not a taxon):

larger; choanocytes in chambers within sponge

water flow:

IN through an ostium,

into an incurrent canal,

into a flagellated chamber,

into an excurrent canal,into spongocoel

(often reduced),

OUT via osculum


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Leuconoid

body plan

water flow:

IN through an ostium, into an incurrent canal, into a flagellated

chamber, into an excurrent canal, into spongocoel (often

reduced), OUT via osculum

Reproduction and Development in Porifera


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Reproduction and

Development in

Porifera

Gemmules: sexual dispersive/resistant phase

(freshwater sponges)

phylum porifera by chesapeake college

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