Zooplankton in the Sea Zooplankton are Animal-like organisms that float and drift on the ocean surface Plankton means “wanderers” Vary in size from jellyfish to microorganisms Most are microorganisms Foundation of the marine food web Important source of food for many other organisms “Spring Blooms” – an increase in zooplankton population Due to increase in phytoplankton – food for zooplankton

2 Types of Zooplankton: Temporary Plankton (These are animals) Embryos or larvae of marine organisms: Fish, crabs, sponges, lobster, clams, and other invertebrates Spend early part of their life cycle floating and drifting near the surface of the ocean When they mature, they settle to the bottom, where they develop into adults Permanent Plankton Remain in the plankton population throughout their entire life cycle The copepod is the most numerous and Tiny shrimp-like animal that feeds on diatoms In turn, it’s food for other larger zooplankton, small fish and whales Copepods are an important link in many marine food chains

Protozoans An amazing group of animal-like protists Carry out all necessary life functions within a single cell Ingestion and digestion Can capture food Example - With a ring of cilia around mouth Ingest food through an oral grove (“mouth”) Food vacuoles take care of intercellular digestion Respiration Aerobic respiration Transport Passive diffusion of O2 and CO2 Food vacuoles transport nutrients inside cell Water balance and excretion Maintain homeostasis (stable internal conditions) with contractile vacuoles Sensitivity Response to external stimuli Reproduction Asexually through binary fission or budding Sexually through conjugation

So far, you have learned about: Prokaryotes – Bacteria Algae and Plants Protista What’s next?

Animals We’ll begin this survey with creatures that are structurally simple, progressing toward those that are complex

What is an animal? Multicellular organism Consumes food Able to move

Exploring Animals…. Animals are the most diverse of living things All animals are multicellular heterotorphs Almost all are (99%) invertebrates, lacking a backbone. No Cell Walls Cells of all animals, except sponges, are organized into structural and functional units called tissue. Active Movement, due to flexibility of cells, and evolution of nerve and muscle tissues. Sexual Reproduction Embryonic Development

Simple Animals – No Body Cavity We will start with the simplest of the animal kingdom sponges, jellyfish, and simple worms These animals lack a body cavity called a coelom, and are thus called acoelomates Major organization of the animal body first evolved in these animals

Animals…

Acoelomate animal: a marine flatworm Acoelomate animal: a marine flatworm. Some the earliest invertebrates to evolve, marine flatworms posses internal organs by lack a true cavity called a coelom.

The Classification of Animals The kingdom Animalia is divided into two subkingdoms: Parazoa (sponges) Eumetazoa (everything else)

Parazoa: Sponges Sponges, Phylum Porifera, are multicellular heterotrophs. Asymmetrical, lacks a definite symmetry NO tissue or organs phylum Porifera, sponges The simplest animals, the Parazoa, lack both difined tissues and organs.

Parazoa: Sponges phylum Porifera, there are around 5000 species, 150 are freshwater Abundant at all depths in the sea Adults are anchored to a submerged object, called sessile. Multicellular, but there is little coordination among cells Sponges can reproduce asexually (by budding or from fragments) or sexually. Exists as aggregates of cells with minimal intercellular coordination

Phylum Porifera Sponges range in size and shape. Up to 2 meters in diameter! Encrusting, boring, finger, tube or vase shaped.

Neighbors Many organisms, including crabs, nudibranchs, mites, bryozoans, and fish live as commensals or parasites in sponges.

Suspension Feeders Sponges are heterotrophic and feed by filtering plankton and other small organisms from the water Passing it out through the large opening (osculum) at one end of the body.

Suspension Feeders Sponges are suspension feeders capturing food particles suspended in the water that passes through their body.

Suspension Feeders The sponges have specialized, flagellated cells called choanocytes These cells move their flagella to draw in water in through pores bringing in food and oxygen and expelling wastes.

Types of Cells Choanocytes, flagellated collar cells, generate a water current through the sponge and ingest suspended food.

Suspension Feeders Choanocytes take in small particles by phagocytosis. Protein molecules are taken in by pinocytosis. Sponges can also absorb nutrients dissolved in the water.

Choanoflagellates Choanoflagellates are solitary or colonial protozoans with a flagellum surrounded by a collar of microvilli.

Choanoflagellates Choanoflagellates resemble sponge feeding cells (choanocytes). Scientists are studying colony formation and cell-to-cell communication in choanoflagellates in search of clues to the evolution of multicellularity.

Sponge Anatomy

Skeletal Framework The skeletal framework of a sponge may be fibrous or rigid. The fibrous part comes from collagen fibrils in the intercellular matrix. Spongin Rigid skeletons consist of needlelike spicules. Calcareous Siliceous Composition and shape the spicules forms the basis of sponge classification.

Sponge Anatomy Many sponges have minute needles of calcium carbonate or silica, or a tough protein called spongin, or both.