Marine Invertebrates Chapter 7

The Classification of Organisms Domain BacteriaDomain ArchaeaDomain Eukarya Kingdom Protista Kingdom Animalia Kingdom Plantae Kingdom Fungi EukaryotesProkaryotes

Animal Kingdom Characteristics of Animals: – Eukaryotic – Multicellular – Heterotrophic – Reproduce sexually – Contain cells lacking a cell wall – Usually capable of movement at some stage in life

Major Phyla of the Animal Kingdom PhylumExamples PoriferaSponges CnidariaJellyfish, sea anemones, corals CtenophoraComb jellies PlatyhelmenthesFlukes, tapeworms NematodaRoundworms AnnelidaPolychaetes, leeches MolluscaSnails, clams, oysters, octopus, squid ArthropodaCrustaceans EchinodermataSea stars, sea urchins Chordatavertebrates

Phylum Porifera Structurally simplest animal Do not form true tissues or organs Mostly sessile – living attached to a surface Variety of shapes, sizes, and colors Simple body plan Filter feed on plankton Reproduce sexually by broadcast spawning Some reproduce asexually when buds break off

Sponge Anatomy

Sponge Anatomy

StructureFunction Pinacocyte Flat cells covering the outer structure Pore cells or porocytes Tube-like cells that allow water to enter

StructureFunction Choanocytes (or collar cells)Cells lining the larger feeding chamber of the sponge; contains a thin flagellum to create a current and collar to trap food particles OculumLarge opening on the top of the sponge through which water exits the sponge

StructureFunction Spicules ( Used for structural support; transparent siliceous or calcareous structures of different shapes and sizes

StructureFunction Spongin ( ) Tough, elastic fibers to help support the sponge Can be sole means of support or found with spicules AmebocytesWandering cells Secrete the spicules and spongin Can transport and store food particles Some can transform themselves into other types of cells

Sponge Feeding Suspensions feeders – animals that eat food particles suspended in the water – Specifically, sponges are filter feeders, suspension feeders that actively filter the food particles

Sponge filtering -

Sponge filtering -

Sponge Reproduction Asexual (one parent) – when branches or buds break off, they will grow into separate sponges identical to the parent Sexual (two parents) – sponges produce sex cells, gametes, nutrient rich eggs and sperm with flagellum – Broadcast spawning

Body Plans Sponges have three basic body plans: – Asconoid – Syconoid – Leuconoid

Asconoid Simplest form A simple tube perforated by holes Central cavity, spongocoel, lined with choanocytes

Syconoid Large tubular body with a single osculum Thicker body wall than asconoid Longer pores that that form simple canals Canals lined with choanocytes (not central spongocoel)

Leuconoid Most complex body plan Vast network of interconnecting canals that eventually lead to one or numerous larger oscula

Classes of Porifera Three classes of Porifera: – Calcarea – Hexactinellida – Demospongiae

Classes of Porifera Class Calcarea – includes sponges with all three body plans – produce large spicules (megascleres) of calcium carbonate. Classes Hexactinellida – only possess leuconoid members – produce six-pointed large and small spicules (mega- and microcleres) made of silica. Class Demospongiae – only possess leuconoid members – may have microscleres and megascleres, spongin, both, or neither