Phyla Porifera and Cnidaria

Where does the majority of the phylum Cnidaria live?

10,000 species of this phylum are predominantly marine.

If you look closely at the tentacles fringing the Aurelia body what will you notice?

8 small gaps in the tentacles. Each gap contians a sense organ, which is sensitive to light, chemicals, and body position.

What is a common sea anemone?

A Metridium.

What is a larva?

A sexually immature form of an animal that is morphologically different from the adult.

What is our example of class Schyphozoa?

A small, common jellyfish Aurelia.

Where are the ostia found?

All over the outside of the body.

What do most hydrozoans like Obelia do?

Alternate polyp and medusa body forms.

What do coral reefs provide?

An important habitat for many species of tropical fish and invertebrates.

What are nematocysts?

Are coiled threads that can be discharged like tiny harpoons to aid in prey capture or in defense against predators.

How do the coral anthozoans obtain food?

Are filter feeders on microscopic particles, but also obtain nutrients from the photosynthesis of symbiotic dinoflagellate algae which live inside their tissues.

What are Medusae?

Are umbrella shaped structures that can swim, and have the mouth and tentacles on the under surface. (jellyfish)

How do sponges reproduce?

Asexually(by budding) and sexually

How are all members of this phylum are characterized?

By having a gastrovascular cavity(one opening mouth) and stinging cells called cnidocytes

How do sea anemones capture prey?

Capture prey that touch the sensitive tentacles. When prey touch the tentacles, cilia lining the pharynx can sweep the prey down into the gastrovascular cavity where the stinging cells immobilize it.

What are the cells in the sponges like?

Cells are not considered to be organized into tissues and these organisms

What do cells within the body take up?

Cells within the body take up particles of food and oxygen, a process known as filter feeding.

What are the three classes of Cnidaria?

Class Hydrozoa, Class Scyphozoa, and Class Anthozoa.

What are the reproduction polyps?

Containing medusa buds are called gonangia.

Over many years what do these skeletons of limestone produce?

Coral reefs

What are corals?

Corals are like sea anemones but are colonial, with each colony consisting of many polyps.

What does each polyp do?

Each coral polyp secretes a protective limestone skeleton.

What maintains a constant flow of water?

Flagella in the gastrovascular cavity.

How is food taken to the mouth?

Food is swept up to the mouth by the ciliated oral arms.

How do sponges obtain nutrients and oxygen?

From the surrounding water by causing water currents to enter the numerous pores called the ostia

How do hydras catch their prey?

Hydras catch their prey by means of cnidocytes, special cells on the tentacles which contain stinging capsules called nematocysts.

What does the class Hydrozoa include?

Includes organisms such as the hydras and the Obelia. The polyp is the predominant body form.

What is Obelia?

Is a colonial hydrozoan found in shallow marine waters attached to substrates such as seaweed or rocks.

What happens when the larvae eventually settles?

It develops into a new polyp colony, and the cycle start again.

What is inbetween these two layers?

Jellylike Mesoglea, which is particulalry thick in jellyfish, so giving rise to their name.

What does this species have?

Long tentacles armed with many deadly cnidocytes to sting and capture prey. These are colonies of polyps.

Where are members of the phylum Porifera located?

Members of the phylum Porifera: 9,000 species of sponges are predominately marine with only 100 species found in freshwater.

What do cnidocytes contain?

Microscopic structures called nematocysts.

What is at the base of the gastrovascular cavity?

Numerous stinging cells on thread-like strucutres called acontia.

What happens to the food after it is digested in the gastrovascular cavity?

Nutrients are transported around around the body as is oxygenated water via a system of radial canals and the circular canal.

What does diploblastic mean?

Only two layers are produced during embryonic development, from which the animal's tissues and organs will develop.

What phylum are sponges, the simplest of all animals in?

Phylum Porifera

What are polyps?

Polyps are cylindrical forms that adhere to a substrate and feed by extending their tentacles which surround the mouth.(Hydra)

What is prey trapped by?

Prey is trapped by the tentacles and four long oral arms. Both tentacles and oral arms are well equipped with cnidocytes which contain nematocysts.

What does the polyp do?

Produces new medusae asexually.

What is the body structure of the Scypha like?

Sac-like body with its basal end for attachment, and upper end where the osculum, is surrounded by long spicules.

What sponge are we looking at in class?

Scypha(Granatia)

What will you see developing on the slides?

See eggs or developing embryos at the blastula stage. These will probably be located behind the choanocytes.

What are radial canals lined by?

Special cells called choanocytes which have flagella.

Where else does support come from in Porifera?

Support comes from the skeleton made up of organic or inorganic spicules.

What does radial symmetry mean?

That an animal has a top and bottom but no head and rear end and no left and right sides.

What is in the center of the cross section of the Scypha?

The Spongocoel that runs the entire length down the center of the sponge.

What should you label on the hydra?

The basal disk, mouth, tentacles, and gastrovascular cavity.

What are the body walls of both polyps?

The body walls consist of two layers of cells, and outer epidermis for protection and an inner gastrodermis for digestion.

What does the name Porifera refer to?

The fact that the body is little more than a sac perforated by numerous pores through which a steady flow of water passes into the body.

How is the biome under threat?

The fragile nature of coral reef organisms is threatened by pollution, souvenir hunters, introduced predators, and the effects of global warming.

What does the class Scyphozoa include?

The jellyfish. The medusa is the predominant body form here.

What should you note?

The mouth connected by the pharynx to the gastrovacular cavity.

What should you locate next?

The ostia(pores) that allow water to enter incurrent canals.

What are two types of protection?

The outer, transparent, protective sheath, the perisarc, and the inner cellular layer, the coenosarc.

What else should you note?

The partions of the gastrovascular cavity called the septa.

What is the member of the hydrozoa Physalia commonly known as?

The portuguese man of war

What is adjacent to the incurrent canals?

The radial canal separated from it by a layer of cells.

What does the class Anthozoa include?

The sea anemones and corals. All are of the polyp body form.

What are two body plans seen in this phylum?

The sessile polyp and the free swimming medusa.

What is the medusa?

The sexual generation producing male and female gametes.

What does the term triploblastic mean?

The term triploblastic is used to describe animals where the typical three germ layers are found in embryonic development.

Where does the water finally leave?

The water finally leaves the body through the osculum.

What do these partciles do?

These food particles get digested in food vacuoles.

What do these develop?

These produce gametes which, at fertilization form a zygote that eventually develops into a planula larvae.

What kinds of organisms are Porifera?

They are sessile organisms attaching themselves to rocks and other substrates with the sac-like body supported by the water.

What happens to the remaining water and indigestible material?

They pass along the radial canals to the spongocoel and then out through the osculum.

How are the Cnidaria unusual in two respects?

They show radial symmetry and they are diploblastic.

In contrast to the Porifera what do the Cnidaria (animals such as hydra, jellyfish, corals, and anemones) have?

They show true tissue organization.

What does the phylogenetic tree of the kingdom Animalia show?

Thought to be very ancient lineage separated from all other phyla in the kingdom due to the lack of true tissues.

How does water pass through this layer of cells?

Through this layer of cells by way of special cells called porocytes.

What do these function as?

To greatly increase surface are for digestion.

Wht do these flagella produce?

Water currents that bring in food articles food particles and oxygen, and also aid in removing small food particles (plankton) from the water.

What happens when the medusa break away from the polyp?

When medusae are mature they break away from the polyp and become free swimming and male or female medusae.

What are the three classes of sponges classified as?

Whether to if their spicules are made up of calcium carbonate, silica, and organic fibers

What are the feeding polyps?

With tentacles called the hydrants.

What are the most obvious features?

four rounded dark gonads which are located within the gastrovascular cavity.

What should you locate at the Aurelia?

the aboral upper and oral lower surfaces.

What should you observe in the Metridium?

the tentacles, oral disk, and the pedal disk which allows for secure attachement to rocks.