gr12b term 1 quiz 1 bio - sponges and cnidarians

what phylum are sponges in? wh?

porifera, because they have pores

how are sponges simple organisms?

they have no tissues, no organs, and most lack symmetry

can sponges regenerate?

yes, if u break one down into individual cells, they will reform a new sponge

sponges - body structure

composed of two layers of independent cells with a jelly-like substance in between

osculum

a sponge’s mouth-like opening

sponges - feeding and digestion

they are filter feeders, they obtain food by filtering small particles out of water, food particles cling to the cells and digestion of nutrients take place within individual cells

sponges - movement

sponges are free-swimming as larvae, but are sessile as adults (stay in 1 place)

sponges - support

within the jelly-like substance between sponge’s two cell layers are archaeocytes, which are amoeba-like cells that secrete spicules, which is the support structures

demospongiae

sponges that have spicules composed of spongin fiber, silica, or both

calcarea

sponges that have spicules composed of calcium carbonate

hexactinellida

sponges that have spicules of silica joined together to form a netlike skeleton

how do sponges respond to stimuli?

they dont have a nervous system, but they have epithelial-like cells that detect external stimuli, such as touch or chemical signals, they respond by closing their pores

how do sponges reproduce?

some asexually, most sexually

how do sponges reproduce asexually

fragmentation - when it breaks into two pieces and forms into two new organisms

budding - grows from a small outgrowth on the parent

gemmules - cells protected by spicules

how do sponges reproduce sexually ?

eggs remain within the organism, sperm is released into the water, the zygote develops into a free-swimming larvae after fertilization

sponge ecology

• food for some tropical fish and turtles

• form habitats for a variety of worms, fishes, shrimp, and symbiotic green algae

• spongin fiber sponges are used for household scrubbing / cleaning

• potential use in pharmaceuticals

what phylum do cnidarians belong to?

cnidaria

contains jellyfish, sea anemones, and contain abt 10000 species, mostly marine

cnidarians - body structure

one body opening, most hv 2 layers of cells

cell layers organized into tissues:

• outer layer - protection

• inner layer - digestion

exhibit radial symmetry

cnidarians - feeding nd digestion

tentacles are armed with stinging calls called cnidocytes containing nematocysts, a capsule that holds a coiled tube containing poision and barbs

nematocysts work like tiny harpoons in response to touch or chemical stimuli, one of the fastest cellular processes in nature

after capture by nematocysts, nd tentacles, prey is brought to the mouth

inner cell layers surrounds the gastrovascular cavity, where cells release digestive enzymes, undigested materials are ejected through the mouth

cnidarians - response to stimuli

have a nerve net that conducts impulses to and from all parts of the body, causing contractions of muscle-like cells in the two cell layers

cnidarians - reproduction

have 2 body forms :

• polyp - tube shaped with a mouth surrounded by tentacles

• medusa - umbrella shaped with tentacles hanging down

cnidarians - diversity

split into 4 classes :

• hydroids: both polyp and medusa stages, many form colonies

• jellyfishes: medusa is dominant, float near the surface of the ocean

• sea anemones and coral: polyp stage is dominant

cnidarian ecology

mutualism is common in cnidarians

habitat for fishes

recreational pleasure to humans from visiting coral reefs

medical use