Marine invertebrates

What are three examples of organisms that belong to Cnidaria

1. Jellies

2. Anemones

3. Corals

Where do jellies spend a significant part of their lives?

Have a significant pelagic life history phase

What is the commonality shared between members that belong to Cnidaria?

They are all equipped with stinging cells called nematocysts

How do anemones feed? Describe in detail

They are passive ambush feeders. They have tentacles equipped with nematocysts that they deploy in the water column. They wait for an organism to come in contact with their tentacles and then the nematocysts will subdue the organism. They will then take the prey item into the digestive cavity through the mouth

Describe the defensive mechanism that anemones have

They withdraw their tentacles when they are disturbed

How do anemones reproduce?

Sexually and asexually

Describe how asexual reproduction occurs for anemones

They bud off anemones if they get cut along the base

Describe how sexual reproduction occurs for anemones

They release eggs and sperm into the water column (usually time it with the tides) and they will find each other. The fertilized eggs spend a very small time in the plankton and then will settle onto the seabed

What are stony corals considered to be? Why?

Anthozoan cnidarians because they don’t have a big pelagic medusa face like the jellies do

What type of symmetry do stony corals have?

Hexacorals (have 6 sided symmetry)

What are stony corals considered to be?

Colonial reef builders

How are stony corals colonial reef builders? Describe the composition of them as well

They have little polyps that build a calcium carbonate cup in which it anchors itself and resides. It will then bud off little clones of the same coral around it.

What is a feature of stony corals?

They have endosymbiotic dinoflagellates called zooxanthellae that live inside of them

What are zooxanthellae? How do corals and the zooxanthellae have a mutualistic relationship?

They are photosynthetic dinoflagellates. They derive nutrients from the coral and reef building by the corals keeps them in well-lit surface waters. The corals as a result get food from the zooxanthellae.

Are there deepwater stony corals?

Yes there are

What is a similarity and difference among the deepwater and shallow water stony corals?

They do the same thing as shallow water corals but they do not have the zooxanthellae so they have to get food by preying with their tentacles

Describe the symmetry of soft corals

They are octocorals (8 sided symmetry)

What are three types of soft corals? How wide are they?

Sea fans, sea whips, sea pens. Only a few mm’s wide

Where are the colonial polyps located on sea fans and sea whips?

On gorgonian protein complex instead of the calcium carbonate cups