AD Sponges and Cnidaria Flashcards
Describe sponges
Mostly marine, some freshwater Shallow to abyssal waters Sessile as adults 4 classes - none monophyletic No muscle or nerve cells Connective materials well developed - form a complex skeletal lattice Size: a few millimetres to more than 1m in diameter and height Many brightly coloured
What is the body symmetry of a sponge?
Radial (sphere,cone,cylinder) or asymmetrical
What is the growth form of a sponge?
Thick,erect,branching,encrusting
What is the sponge architecture?
No true tissues or organs System of water canals Surface perforated with openings These are incurrent pores or ostia Water enters here Pores open into the atrium Water leaves the atrium through the osculum
Why is there a constant flow of water through incurrent pores into atrium and out the osculum of the sponge?
It carries food particles and oxygen and excretion products containing carbon dioxide
What is the outer surface of the sponge covered by?
Pinacocytes which make up the pinacoderm
In a sponge, beneath the pinacoderm is the mesohyl. What is this?
A gelatinous protein matrix
Contains skeletal material and amoeboid cells.
The skeletal components are spicules of calcium, carbonate or silica, spongin fibers.
What are archeocytes?
Amoeboid cells
They are phagocytic and function in digestion. They are totipotent.
What is a choanocyte?
Line the interior of sponges- make up the choanoderm
Have a flagellum, collar of microvilli and a cell body
Flagella beat to create the active pumping of water through the sponge
The collar is where nutrients are are absorbed
The body plan of the sponge is based on 1 of 3 designs. What are these designs?
Asconoid - a hollow cylinder
Syconoid - interdigitating inpockets and outpockets
Leuconoid - Complex network of water vessels
What sized particles can and cannot enter the ostia and why?
Large particles (more than 50um) cannot enter the ostia - pinacocytes consume them by phagocytosis
Medium sized particles (1um to 50um) are trapped in the ostia and are consumbed by archaeocytes - these cells partially excrude themselves through the walls of the ostia
Small particles (0.1-1.5um) pass through the ostia and are captured and consumed choanocytes.
Choanocytes typically capture 80% of a sponge’s available food supply
What is suspension feeding?
Capturing suspended food particles
from water
by passing a current of water through the body
Some sponges harbour photosynthesising mutualists (green algae, dinoflagellates,
cynobacteria)
Sponges of the family Cladorhizidae are unusual in being carnivores - typically feed
by capturing & digesting whole animals (small crustaceans) with their spicules
Describe the skeleton of a sponge?
Usually an endoskeleton
Fibrous - made of spongin
Spicules - calcium carbonate or silica
Describe sexual reproduction in sponges
Sexual = hermaphrodites
Produce eggs and sperm at different times
However the barrel sponge is dioecious
Sperm is released into the surrounding area via the osculum
Can look as if the sponge is smoking
Sperm is captured by female-phase sponges via the ostia
Zygote develops into a ciliated larva
Some sponges release larva, some keep them for a while
Once the larva are in the water column, they settle and develop into juvenile sponges
Describe asexual reproduction in sponges
Produce buds or gemmules (packets of several cells inside a protective covering)
