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Zoology
Porifera
Attn Grabbers:
1. What is the substance that makes the shells of diatoms?
2. What is the phylum name of diatoms?
3. What % of the world’s O2 comes from diatoms?
Porifera Notes
General:
 “porus” means pore and “fera” means to bear
 Primarily marine animals, although some freshwater varieties exist.
 ~9000 species
 Vary in size from less than a CM to several meters across/tall
 Strong evidence from cell structures suggest that sponges as well as most animals
evolved from Protista ancestors.
 Sessile: live their entire adult life attached to a single spot.
 Classified by skeleton type: Hard of Soft
Body Plan:
 Asymmetrical or radial symmetric
 Composed of three cell types
Central Cavity, or a series of branching chambers, water circulates here. Water leaves
through an opening called the Osculum. This circulation of water provides a simple way
to feed, respire, circulate, and excrete.
No tissues or organs
3 Cells Types:
Pinacocytes: thin, flat cells, which line the outer surface of sponge.
Able to contract and slightly change form of sponge.
Help to regulate water circulation in body wall.
Mesohyl (middle matter) jelly like layer where Amoeboid cells help with reproduction,
food transportation and storage, and skeletal elements.
Choanocytes (funnel cell) inner most layer
Flagellated cells circulate water through sponge and filter for food particles. At the end
of the cell is a collar , lined with microvilli to filter food.
These cells show evolutionary evidence for the connection to choanoflagellate Protista.
Skeleton: Two Types of Sponges: Hard and Soft. Hard sponges are made of
microscopic needle like spikes called Spicules. They are formed by the amoeboid cells
The spicules are made of CaCO3 and Silica. Soft sponges are made of Spongin, made of
collagen.
Feeding: filter particles the range from 0.1um to 50um.
Mostly bacteria, algae, Protista, and organic matter.
Digestion is intercellular, moved to the food vacuole, and digested by the lysosome.
Sponges reduce the turbidity of water, natural filters.
A sponge 1cm in diameter and 10cm high can filter about 20L of water a day depending
on their size.
No nervous system to coordinate body movement. Most reactions result from individual
cells reacting to stimulus.
Reproduction: Monoecious: both sexes in same individual
Sexual, but cannot reproduce with themselves.
Some choanocyte cells lose their collar and form either sperm or eggs.
Sperm and egg released into water and fertilization happens here. External
Larva develop, carried by water, settles, and grows into a stationary adult.
Asexual: form a resistant capsule called a gemmule which contain masses of amoeboid
cells. If the parent dies due to hard conditions, the gemmule can survive extreme
temperatures and drying. When conditions are better the gemmules develop into a
sponge
Sponges have the ability to regenerate. Broken portions can regenerate into a new
sponge.