Porifera and Cnidaria

Meaning of Phylum "Porifera"

pore-bearing

Multicellular

different cell types (-cytes) perform different functions

-cyte

cell

Water Vascular System

series of pores, canals, and chambers that help circulate water through the body of a sponge

Habitat for sponges

all aquatic; mostly marine

Sponge body symmetry

radial or none at all (asymmetrical)

Sponge life cycle stage that is sessile

adult

Sessile

non-moving

Intracellular digestion

type of digestion in which small food particles must first be absorbed into individual cells, which then use lysosomes to break down the food particles in food vacuoles

Mesohyl

non-living gelatinous protein that contains other cell types in a sponge

Spongin

flexible structural material secreted by spongocytes; found in all sponges

Spicules

rigid structural material secreted by sclerocytes; found only in marine sponges

Methods of asexual reproduction in sponges

fragmentation, budding, or gemmules (internal buds)

Amphiblastula

Free-swimming larva that develops from a sponge zygote

Metazoan

multicellular animal (Sponges were the first metazoans.)

Level of organization found in sponges

cellular

Division of Labor

the breaking down of the job of staying alive into separate, smaller tasks, which are performed by different cells in sponges and by different tissues in cnidarians

Pinacocytes

thin, flat cells that cover the exterior surface and some interior surfaces of sponges; they provide protection and are somewhat contractile to help regulate the surface area of the sponge

Myocytes

modified pinacocytes arranged in circular bands around the oscula or pores of sponges where they contract to help regulate the rate of water flow

Porocytes

tubular cells that form the pores or passageways through which water circulates from one canal or chamber to the next inside a sponge

Choanocytes

cells that have a flagellum surrounded by a collar and line canals and chambers where they create a water current, strain food particles from the water, and pass the food on to a neighboring archaeocyte for digestion

Archaeocytes

amoeba-like cells that move about in the mesohyl of sponges and carry out several functions including receiving food particles for digestion from choanocytes and transporting nutrients to other cells; differentiating into any other type of more specialized cell in the sponge and forming into gametes during adverse conditions

Spongocyte

specialized cell type that produces the flexible structural material, spongin, in all sponges

Sclerocyte

specialized cell type that produces rigid structural materials, spicules, in marine sponges

Monoecious

having both sexes in "one house"; also known as hermaphroditic

Ostia

external incurrent openings that cover the outer surface of a sponge

Osculum

external excurrent opening where water and wastes exit a sponge

Prosopyle

pore between incurrent and radial canals inside a sponge

Apopyle

pore between radial canal and spongocoel inside a sponge

Incurrent Canal

passageway inside a sponge that is lined with pinacocytes

Radial Canal

passageway inside a sponge that is lined with choanocytes

Spongocoel

hollow central cavity of a sponge

Water flow through a sponge

Water flows in through the Ostia to the...

Incurrent canal...

Through the prosopyle,

Formed by porocytes to the...

Radial canal,

Lined with choanocytes...

Through the apopyle...

Into the spongocoel...

Out of the osculum,

Which is surrounded by a ring of myocytes.

Meaning of phylum "Cnidaria"

nettle-like

Level of organization found in cnidarians

tissue

Tissue

a group of cells performing a similar function

Diploblastic

two tissue layers

Endoderm

inner tissue layer lining the gastrovascular cavity of cnidarians that circulates food and fluids in the digestive cavity

Ectoderm

outer tissue layer that provides protection and movement in cnidarians

Extracellular digestion

digestion that takes place outside of cells in a large chamber and then nutrients are absorbed by surrounding cells; allows for the digestion of larger food particles with more energy value

Habitat for cnidarians

all aquatic; mostly marine, but some freshwater

Cnidarian body symmetry

radial

Gastrovascular cavity

a large chamber inside of a cnidarian with a single opening that serves as both mouth and anus

Nematocysts

stinging organelles housed within cnidocytes on the tentacles of cnidarians; used for defense and obtaining food

Cnidocytes

cells that contain nematocysts; found on the tentacles of cnidarians

Cnidocil

the "trigger" that, if touched, causes the forceful expulsion of a nematocyst from a cnidocyte

Nerve Net

Nerve cells arranged in a network in the mesoglea layer of cnidarians; connected to some simple sense organs for balance and light sensitivity; allows coordinated rhythmical muscle contractions similar to those found in the human stomach and intestines

Mesoglea

non-living jelly-like material found between the two tissue layers of cnidarians; contains the nerve net

Polymorphism

"Many forms"'; the coexistence of two or more distinct forms of individuals in the same population; cnidarians may exist as polyps, medusas, or planulas

Polyp

form of cnidarian adapted to a sedentary or sessile life; (hydroid form)

Hydranth

nutritive/feeding polyp of a cnidarian

Gonangium

sexually reproductive polyp of a cnidarian

Medusa

form of cnidarian adapted for a floating or free-swimming existence (jellyfish form)

Planula

larval form of cnidarian that is able to move around using cilia

Alternation of Generations

a life cycle that exists in some cnidarian species in which they alternate between polyp (asexual) and medusa (sexual) stages; also known as metagenesis

Sensory cells

cells scattered among the other epidermal cells of cnidarians, especially around mouth and tentacles; have flagella which are sensitive to chemicals and touch; send messages to nerve net

Epitheliomuscular cells

large cells found in the epidermal tissue of cnidarians; make up 80% of the ectoderm; serve as protective covering and for movement

Hydrozoa

class of cnidarians that are mostly marine & colonial; most have both medusa and polyp stages; Examples: Hydra, Obelia & Portuguese man of war

Scyphozoa

class of cnidarians that are mostly marine; mostly medusa stage; Examples: true jellyfish

Anthozoa

class of cnidarians that exist only the polyp stage; all are marine; form coral atolls, islands, and reefs; Examples: sea anemones and corals

Interstitial cells

cells found in both tissue layers of cnidarians that have the ability to specialize and become other cell types when needed