Phylum Porifera

Sponges and Cnidarians

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INVERTEBRATES

Most of the more than one million animal species on Earth are invertebrates, or animals without backbones. Apart from the absence of a backbone, however, invertebrate groups have little in common with each other; rather, they make up a highly diverse and largely unrelated group of animals. Lobsters, insects, spiders, worms, jellyfish, clams, crabs, sea stars, and sponges are a few of the most familiar invertebrates.

Multiple Choice

What is an invertebrate?

• An animal with a backbone
• a mammal
• An animal without a backbone
• birds

Sea sponge

The sponges (phylum Porifera) are among the simplest of the invertebrates. Sponges can be described as organized masses of specialized cells that carry out bodily functions. Most sponges are ocean dwellers, but a few are found in fresh water. Approximately 5,000 species have been described.

VIDEO!!

Multiple Choice

This picture is an example of which group of invertebrates?

• Segmented worms
• Fish
• Sponges
• Arthropods

Sponges do not have nervous systems, so they don't react to the world around them. Sponges are in the shape of a big "U." On the outside of the U are protective cells made of calcium carbonate, but on the inside are these very special cells= FLAGELLATED COLLAR CELLS. Those flagella are constantly moving and keeping the water circulating inside of the sponge. Water is sucked in through holes PORES in the side of the sponge. When the water moves through the sponge, tiny food particles are filtered out of the water by the flagella. Then the water gets pushed out of the sponge through a hole called an OSCULUM.

Multiple Choice

Sponges use pores to 

• move from place to place.
• filter food from the water.
• defend themselves.

The phylum Cnidaria consists of about 9,000 species of jellyfish, hydras, and corals. Cnidarians are radially symmetrical animals that do not have circulatory, respiratory, and excretory organs. They have nerve cells organized in a net that can respond to touch and chemical cues, but it is not a true nervous system. VIDEO!!

Cnidarians are carnivores and use their tentacles to feed on plankton and other small organisms in the water. They trap food using their stinging cells. By the STINGING CELLS the prey is paralysed. Food is digested in the DIGESTIVE CAVITY:

Cnidarians have the ability to reorganize and regenerate their bodies. The oldest cnidaria is arguably corals in a reef, which have been known to live as a single sheet for more than 4,000 years. In contrast, some polyp types only live 4–8 days. 

There are two different body styles of the Cnidarians: Polypoid and Medusae.

Multiple Choice

I have a digestive cavity with one opening, and have tentacles.  I am a hydra.

• Echinoderm
• Cnidarian
• Arthropod
• Mollusk

Multiple Choice

This form of cnidaria is known as a _______.

• polyp
• medusa

Multiple Choice

This form of cnidaria is known as a __________.

• medusa
• polyp

Multiple Choice

Jellyfish use their.................. to catch their prey.

• osculum

• stinging cells

• digestive cavity

• flagellated collar cells