Chapter 6: Small Marine Animals Zooplankton

1. What is an animal? (Uni/multicellular? Auto/heterotrophic?)

2. How many species of animals are there on Earth?

3. How many species of animals are in the Earth’s Oceans?

4. In what kingdom do scientists place unicellular animal-like organisms?

DO NOW: What is an animal?(p141)

Zooplankton

• Organisms that float and drift are considered part of the plankton population.

• Phytoplankton – similar to plants

• Zooplankton – similar to animals

• Zooplankton include both single- celled Protista & some multicellular animals such as jellyfish.

Zooplankton

• Zooplankton are divided into 2 main groups:

1. Temporary zooplankton

2. Permanent zooplankton

1. Temporary: only spend larval stage as planktonic organisms.

2. Permanent: spend entire life cycle as planktonic organisms.

Temporary Zooplankton

• Some animals are planktonic during their larval stages (early part of life).

• Some fish, crabs, sponges, lobsters, and clams.

• Once they mature they settle to the bottom of the ocean and develop into adults.

Planktonic Organisms

Barnacle Larva

Shrimp Larva

Octopus Larva

Hermit Crab Larva

Sea Anemone Larva

Flatworm Larva

Sea Cucumber Larva

Permanent Zooplankton

• Species that remain in the plankton population for their entire life cycle.

• Foraminifera, Copepods, Radiolaria

Foraminifera

• A unicellular Protist.

• Encased in a shell made of calcium carbonate.

• Parts of their cytoplasm flows out through holes in the shell, and forms a sticky surface to catch food.

• The shells of dead Foraminifera can accumulate as a thick chalk substance on the ocean floor.

Copepods

• Tiny shrimp-like animal that feeds on phytoplankton such as diatoms.

Radiolaria

• A unicellular Protist.

• Has cell wall made of silica.

• Has long spikes for buoyancy and protection.

• Whales are filter feeders that feed on large schools of krill.

• Mollusks (mussels and clams) depend on plankton as their main food source.

• Smaller fish feed on plankton until they are large enough to eat other organisms.

Plankton as a food source

Protozoans

• Unicellular, animal-like organisms.

• Classified in the Protista kingdom

• Split up into 3 major groups: 1. Ciliophora

2.Zoomastigina

3.Sarcodina

The Ciliophora:

• Largest group of protozoans

• Freshwater and saltwater species.

• They all have cilia: • The Spirostomum use cilia for locomotion.

• The Stylonychia use their cilia to crawl along substrates.

• The Vorticella live anchored to a substrate, they use the cilia for feeding.

Zoomastigina

• They move through the water with a whip-like flagella.

• They live in freshwater, saltwater, and as parasites inside organisms.

• Members include the Euglena and Dinoflagellates. • both of which can take in and make their own food.

Sarcodina:

• They live on the surface of substrates.

• Move by cytoplasmic extensions called pseudopods.

• moving pseudopods can engulf food particles.

• Includes the forams and radiolarians.

• Sponges are multicellular marine animals.

• They are in the phylum Porifera.

• They can be found in the benthic zone from the intertidal zone to the bottom of the ocean.

Sponges

Sponge sections

• Sponges have 2 layers of cells:

1. inner layer is called the endoderm

2. outer layer is called the ectoderm

• Between the two layers is the jelly-like mesenchyme.

Sponge Anatomy

• Ostia = small pores.

• tiny food particles and plankton enter the sponge here.

• Osculum = large hole at top of sponge.

• water and waste exit here.

Sponge Anatomy

• Collar cells = found inside the sponge.

• have flagella which beat back and forth to produce a current which pumps water through the sponge.

• Digestion: Collar cells and cells called amebocytes (found in mesenchyme) trap and digest food.

• Respiration: Water flowing through the ostia brings in dissolved O2. CO2 diffuses out of sponge cells and leaves through the Osculum.

Sponge Life Processes

• Responsiveness: Sponges lack a nervous system.

• They have muscle-like cells called myocytes. When these cells contract the ostia close preventing water (and dangerous substances) from getting in.

Sponge Life Processes

• Euspongia (the bath sponge) lives in warm tropical waters.

• At one time this sponge was widely harvested.

• Cliona (the yellow boring sponge) grows on the shells of clams and other shellfish.

• It uses an acid to bore holes into shells and attach to them.

Types of Sponges

• Euplectella (Venus’ flower basket) lives at great depths. It is a tubular sponge composed of a delicate network of glass spicules.

• Ircinia (vase sponge) is found on the sandy bottom near coral reefs.

Types of Sponges

• Adult sponges release sperm and eggs into the water.

• The two combine to produce a fertilized egg cell called a zygote.

• Cell division occurs until there is a ball of cells called a morula.

Sponge Life Cycle

• Rotifers are microscopic but are also multicellular.

Rotifers:

• A microscopic, multicellular animal.

• It lives within a box shaped compartment made of calcium carbonate.

Bryozoans