Phylum Porifora & Phylum Cnidaria

Chapter 9 Notes

Phylum Porifora

• • • • • Sponges - porifora = “bears pores” Habitat: Mostly Marine Sessile (cannot move) Sexual or Asexual – Monoecious – both sexes in the same individual – Asexual gemmules – released when parent dies in winter – Asexual regeneration Filter feeders – Eat particles

Phylum Porifora

• • • • • • Loosely organized cells No tissues or organs Evolutionarily, most primitive animals ~9,000 species Size from <1cm - 2m Asymmetrical/ superficially radially symmetrical Central cavity & branching chambers – Used to circulate water

Phylum Porifera

• 3 Types of Cells – Pinacocytes “pea-knock-o-cytes” • Thin, flat cells • • Line outer surface of sponge Porocytes – regulate water circulation – Mesenchyme cells • “Amoeboid cells” • • • Middle, jellylike layer Reproductive cells Secrete skeletal elements • Transport and store food – Choanocytes “funnel - cell” • Inner layer • • • “collar cells” – ring of cells with microvilli surrounding a flagellum Flagellated Creates water currents through the sponge

Phylum Porifora

• Sponges skeleton – Spicules - Microscopic needlelike spikes – Spongin – fibrous protein made of collagen

Important Groups of Porifora

• • • Calcarious Sponges – Spicules made of calcium carbonate – – Spicules are needle shaped All marine Glass Sponges – Spicules made of silica Bath Sponges – Colorful sponges – Siliceous spicules or spongin or both – 1 family of freshwater sponges

Phylum Cnidaria

Phylum Cnidaria

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Number of Species

9,000+ Species • •

Habitat

All aquatic Mostly Marine •

Food Source

Small crustaceans & fish

Phylum Cnidaria

• • Unique Characteristics: Important in coral reef ecosystems Have specialized cells ‘cnidocytes’ – – Epidermal/gastrodermal cells Used in defense, feeding, and attachment • Produce cnidae – a fluid-filled, intracellular capsule enclosing a coiled, hollow tube – Ex: Nematocysts (a type of cnidae) – Contain barbs to penetrate prey

Phylum Cnidaria

• • • Important groups: Jellyfish Anemones Corals

Phylum Cnidaria

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Body Structure

Radial or biradial symmetry (oral/aboral) Have tissues! (…and I don’t mean kleenex…) Diploblastic (endoderm + ectoderm +mesoglea) Specialized cells – – Food gathering – Defense – Digestion – Absorption Medusa (dioecious & free swimming) or polyp (sessile & asexual) •

Skeletal Support

Hydrostatic skeleton – water-filled gastrovascular cavity

Phylum Cnidaria

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Digestion/Food Capture:

Nematocysts – entangle and paralyze prey Tentacles contract to bring food to the mouth Enzymes and lysosomes break down the food in gastrovascular cavity Makes a sort of soupy mixture Phagocytosis

Phylum Cnidaria

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Muscular Movement:

Pulsate muscles to move tentacles in an inchworm fashion and glide Nutritive muscular cells move materials in and out of the gastrovascular cavity •

Nervous Communication:

Primitive nerve net – does not lead to anything

Excretory Waste Removal & Respiration

• • Both processes occur in the gastrovascular cavity Cnidarians have a large surface-area-to volume ratio – All cells are near body surface – O 2 , CO 2 , and nitrogenous wastes exchange by diffusion

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Reproduction

Mostly dioecious Sperm & egg released from gastrovacular cavity – – Planula = ciliated, free-swimming larva  polyp forms Polyps reproduce by budding  forms medusa Alternation of generations life cycle