Chapter 8 Lower Invertebrates Karleskint Turner Small What

Chapter 8 Lower Invertebrates Karleskint Turner Small

What Are Animals? • Animals: 1. are multicellular 2. have eukaryotic cells without cell walls 3. cannot produce their own food, depend on other organisms for nutrients 4. can actively move 5. invertebrates = animals that lack a vertebral column (backbone) 6. vertebrates – animals with a vertebral column 7. majority of animals in sea are invertebrates

Body Structure • • Dorsal – Top Ventral – Bottom/belly Anterior – Head Posterior - Tail

Body Symmetry • Asymmetry – No symmetry • Radial – Arrangement of body parts around a central axis - Top & bottom, No front, back, or right & left sides – Allows for organism to take in stimuli from all sides

Bilateral symmetry – 2 similar halves on either side of a central plane • Adaptation for movement

Cephalization • Concentration of sensory & brain structures in the Anterior region No-cephalization

Sponges • Phylum Porifera • Basic characteristics: – Simple – Asymmetric – Sessile: Permanently attached to a solid surface – Have many shapes, sizes and colors – Shape often determined by shape of bottom sediments, material on which they are growing and local water currents

Sponges have specialized Cells but NO Tissues • Most primitive animals on Earth

Sponge Structure and Function • Body is built around a system of water canals – Ostia: Tiny holes or pores through which water enters the sponge’s body – Spongocoel: Spacious cavity in the sponge into which water flows – Osculum: Large opening through which water exits from the spongocoel

Sponge Structure and Function • Lacking tissues, sponges have specialized cells – Collar cells (Choanocytes) use their flagella to provide force for moving water through the sponge’s body – Amoebocytes: Cells that resemble amoebas, and can move through sponge body • Transport materials

Sponge Structure and Function • Structural materials – Spicules: Skeletal elements that give support to a sponge’s body, produced by specialized cells and composed of calcium carbonate, silica or spongin – Spongin: A protein that forms flexible fibers

Sponge Structure and Function • Sponge size and body form – Size is limited by water circulation – Asconoid: Simplest form; tubular and always small, found in clusters – Syconoid: Sponges that exhibit the first stages of body-wall folding – Leuconoid: Sponges with the highest degree of folding, which have many chambers lined with collar cells

Osculum Choanocyte Ostia Spicules Amoebocyte

Sponge Structure and Function • Nutrition and digestion – Sponges are suspension feeders – feed on material suspended in seawater – Sponges are also referred to as Filter Feeders – they filter food from the water – Large particles are engulfed and digested by pinocytes and archaeocytes – Collar cells trap ~ 80% of food which consists of small particles (0. 1 to 1. 0 micrometers in size) – Sponges are one of the few animals that can capture such small sized particles

Sponge Structure and Function • Reproduction in sponges – Asexual reproduction • Budding: Group of cells on the outer surface of the sponge develops and grows into a tiny new sponge, which drops off and establishes itself • Fragmentation: Production of a new sponge from pieces that are broken off by physical processes, e. g. , waves, storms, predators – Sexual reproduction • Most sponges are Hermaphrodites • Larval stage is called a planktonic Amphiblastula

Ecological Roles of Sponges • Competition – Compete aggressively with corals and bryozoans for attachment space • Predator-prey relationships – Few species eat sponges • Spicules are like needles • Some produce chemical deterrents – A few species of bony fish and molluscs and sea turtles (especially the hawksbill) will eat sponges

Ecological Roles of Sponges • Symbiotic relationships – Sponges are Mutualistic or Commensalistic hosts to many organisms • e. g. symbiotic cyanobacteria – Many organisms (shrimp, fish) live within the canals or spongocoel, for protection and to take advantage of water flow

Ecological Roles of Sponges • Sponges and nutrient cycling – Boring sponges (family Clionidae) recycle calcium as they burrow into coral and mollusc shells

Sponge Dye in the Ocean • http: //www. youtube. com/watch? v=8 ue. Kl. Shb 9 Ls

Kingdom: Animalia Phylum: Cnidaria Jellyfish, Anemone, Corals

Cnidarians: Animals with Stinging Cells • Phylum Cnidaria • Include jellyfish, hydroids, corals and sea anemones • Named for their Cnidocytes—Stinging cells • Cnidocytes are used to capture prey and protect the animal

Organization of the Cnidarian Body • Often exhibit 2 body plans within their life cycles: – Polyp: Benthic form characterized by a cylindrical body with an opening at 1 end, i. e. , the mouth which is surrounded by tentacles – Medusa: A free-floating stage (jellyfish)

Stinging Cells • Cnida: Stinging organelle within a cnidocyte, which may function in locomotion, prey capture, or defense – Nematocysts: Spearing type cnida, which are discharged when the cnidocill—a bristle-like trigger —contacts another object

Stinging Cells • Stinging cells also triggered by certain chemical substances released by prey • Dangerous species – Box jellyfish (can kill within 3 -20 minutes)

Kingdom: Animalia Phylum: Cnidaria Class: Hydrozoa “water animals”

Types of Cnidarians • Hydrozoans (class Hydrozoa) – Mostly colonial – Colonial forms contain 2 types of polyp: • Gastrozooid = Feeding polyp • Gonangium = Reproductive polyp – Hydrozoans known as hydrocorals secrete a calcareous skeleton, e. g. , fire coral – Some produce floating colonies • e. g. Portuguese man-of-war

Portuguese Man of War • http: //www. youtube. com/watch? v=x. Tg. LTb XJrf. M&list=PL 355 D 512277 EFFA 06&index =23

Ex: Physalia Portuguese man-of-war • • Colony of medusae and polyps Gas-filled float: Tentacles measure up to 65 ft Preys mostly on small fish-poison can be painful and even fatal to humans

Phylum: Cnidaria Class: Scyphozoa “cup animals” True Jellyfish

Phylum: Cnidaria Class: Scyphozoa • Cup animals • Jellyfish • Medusa is the dominant form of the life cycle • Pulsating motions of the cup propel the jellyfish through the water • Some nematocysts cause severe pain and even death to humans

Types of Cnidarians • Jellyfish • Scyphozoans—True jellyfish (class Scyphozoa) • Considered members of the plankton • Medusa is predominant life stage • Photoreceptors: Sense organs that can determine whether it is dark or light – Box jellyfish (class Cubozoa) • • Box-shaped bells Relatively strong swimmers Tropical Voracious predators, primarily of fish

Phylum: Cnidaria Class: Anthozoa “flower animals” Sea Anemone & Coral

Types of Cnidarians • Anthozoans (class Anthozoa) – Include sea anemones, corals and gorgonians – Sea anemones • Benthic, all adults are sessile • Though sessile, many can change locations

Phylum: Cnidaria Class: Anthozoa • “Flower Animals” • Polyp form dominant • Sea Anemone 1. Attach themselves to rocks and other submerged objects 2. Feed on fishes and other animals

• Corals 1. Small polyps live in colonies 2. calcium carbonate skeleton 3. 30 degrees N or S of the equator 4. Shallow depths in warm, clear water 5. Zooxanthellae

Types of Cnidarians • Anthozoans (class Anthozoa) – Coral animals • Polyps that secrete a hard or soft skeleton • Hard, stony corals • Form reefs along with coralline red algae and calcified green algae

Types of Cnidarians • Anthozoans (class Anthozoa) – Soft corals • Polyps that form plant-like colonies

Nutrition and Digestion • Gastrovascular cavity: Central cavity where cnidarians digest their prey – Waste products forced back out mouth • Many hydrozoans and anthozoans are suspension feeders • Jellyfish and box jellyfish are carnivorous, eat fish and larger invertebrates • Sea anemones generally feed on invertebrates, some large species feed on fish, shallow water species have symbiotic algae

Reproduction • Scyphozoans – in adult jellyfish and box jellyfish, sexes generally separate – medusae (sexual stage) release gametes into the water column for fertilization – planula larvae settle, grow into polyps, and reproduce medusa-like buds asexually – immature buds are released into the water column to grow into mature medusae

Ecological Relationships of Cnidarians • Predator-prey relationships – Cnidarians are predators – Sea turtles, some fish and molluscs prey on hydrozoans and jellyfish

Ecological Relationships of Cnidarians • Symbiotic relationships – Portuguese man-of-war and man-of-war fish – Reef-forming corals and zooxanthellae • Algae provide food and oxygen to coral through photosynthesis • Coral provides nutrients and carbon dioxide to algae through respiration – Sea anemones. . . • and Clownfish • and the Hermit crab

Phylum: Ctenophora Comb jellies

Ctenophores • Phylum Ctenophora • Planktonic, nearly transparent • Ctenophore structure – Named for 8 rows of comb plates which the animal uses for locomotion • Are composed of large cilia – Exhibit radial symmetry – Lack stinging cells – Adhesive cells (sticky) – Bioluminescent

Phylum: Ctenophora • Comb jelly - eight comb like rows of cilia • Move through water by beating their cilia • Colloblasts-secrete a sticky substance that binds to their prey • Apical organ-senses orientation in the water • Most hermaphroditic • Bioluminescence-production of light • Occur in large swarms near the surface of the ocean

Neon Killers • http: //www. youtube. com/watch? v=39 qe 0 E ajb. IA&list=PL 355 D 512277 EFFA 06&index =106

The Evolution Of Bilateral Symmetry • Bilateral symmetry – Body parts arranged such that only one plane through the mid-line divides animal into similar right and left halves – Allowed for streamline body shape increasing mobility – Favored concentration of sense organs at one end of animal (Cephalization)

Flatworms • Have flattened, bilaterally symmetrical bodies with a definite head and posterior end

Flatworms • Types of Flatworm – Turbellarians are mostly pelagic, and are invertebrates living between sediment particles – Turbellarians have sensory receptors in head region to detect light, chemicals, movement and help maintain balance – Flukes usually have complex life cycles – Tapeworms live in the host’s digestive tract

Flatworms • Ecological role of flatworms – Turbellarians: • Turbellarians funnel nutrients to higher trophic levels • Prey for higher-level consumers – Parasitic flatworms: • Can regulate population size by lowering fitness of host

Ribbon Worms • Phylum Nemertea – Most are benthic – Resemble flatworms but are longer with thicker bodies – Sexes are separate, fertilization external – Carnivorous – Feed on annelids and crustaceans – Capture prey with proboscis (tube extending from mouth)

Ribbon Worms • Ecological role of ribbon worms – Prey organisms for higher consumers – Burrowing in sediment moves nutrients to surface – Abandoned burrows can serve as habitat