Marine Biology Test 2

Zygote

The initial cell formed when a new organism is conceived

Morula

A solid ball of cells formed from a zygote

Blastula

A hollow ball of cells that develops from the morula

Gastrula

The stage in embryonic development that forms germ layers

Organogenesis

The formation of tissues and organs from germ layers

Protostomes

Organisms where the blastopore becomes the mouth first (ex: mollusks, annelids, arthropods)

Deuterostomes

Organisms where the blastopore becomes the anus first (ex: echinoderms, chordates)

Ectoderm

The outer layer of cells that forms the skin and nervous system

Mesoderm

The middle layer of cells that forms muscles, bones, and the circulatory system

Endoderm

The inner layer of cells that forms the gut and internal organs

Coelomate

An organism with a true body cavity lined with mesoderm (ex: earthworm, human)

Pseudocoelomate

An organism with a body cavity partly lined with mesoderm (ex: roundworms)

Acoelomate

An organism with no body cavity (ex: flatworm)

Asymmetry

A body plan with no definite shape (ex: sponges)

Radial symmetry

A body plan arranged around a central axis (ex: jellyfish)

Bilateral symmetry

A body plan where left and right halves mirror each other (ex: humans, worms)

How do sponges obtain their needs?

They are filter feeders, they draw water through their pores and trap food with choanocytes

How do sponges reproduce?

Asexually: budding (a piece breaks off and regenerates)

Sexually: external fertilization (egg and sperm meet in the water, fertilize, become larva, attaches to a solid substrate, and then grow into sponges)

How do sponges protect themselves?

Spicules:

• Silicous (silica, glass-like)

• Calcareous (shell-like)

• Spongin (sponge-like)

Where do sponges live?

A variety of marine habitats (or freshwater), can range from warm tropical seas to cold polar waters

How do cnidarians obtain their needs?

They use tentacles to paralyze and eat their food

How do cnidarians reproduce?

1. Female and male eject sperm and eggs

2. Fertilizes and forms a blastula

3. Becomes a larva

Embryo, morula, blastula, planula, polyp (sometimes)

How do cnidarians protect themselves?

Nematocysts

Where do they live?

Three cnidarians

Sea anemone, jellyfish, coral

2 threats to coral

Climate change, overfishing, pollution