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Home , Phylum

The Diversity of 1: Animals are in Eukarya

Chapter 23 • Immediate ancestors are a type of Protista

Kingdom Animalia Phylogeny of Animalia (overview)

• Key features Multicellular Heterotrophic: gain energy by consuming other organisms No walls Motile at some stage of their Most (but not all) can respond actively to stimuli due to their nerves and muscles

Phylum Porifera: “pore bearers” Porifera: “pore bearers” • Key features No tissues Tissues are groups of similar cells that work together – Example: Groups of muscle cells muscles All other animals have tissues

Lined with flagellated collar cells Flagella beat to create water current Function in food collection, digestion and gas exchange

1 Phylum : Phylum Porifera: “pore bearers” “cnid” = nettle; all have stinging cells • Water flows in through small pores, and out through osculum

• Spicules : Spiky structures that provide structure and some protection

Phylum Cnidaria: Key features Radial vs bilateral

• Radial symmetry • and medusa forms • • Two tissue layers Body wall (=epidermis) from ectoderm Ecto = outside Lining of gastrovascular cavity from endoderm Endo = inside

Polyp and medusa forms Phylum Cnidaria: Key features

• Gastrovascular cavity Feeding/digestion Medusas Gas exchange Hydrostatic skeleton Water pressure only Only one opening  • Simple : No brain or nerve cords Polyps • = stinging cells

2 Phylum Cnidaria Phylogeny of Animalia (overview)

• Focus on cnidocytes Contain a specialized stinging structure within a toxin-filled sac. Stinger forcibly ejects Hollow; injects toxins Barbed; hangs on Most toxic: box jellies = wasp

• Dead cnidarians can still sting!

Phylum Platyhelminthes: Phylum Platyhelminthes: Key features The • Bilateral symmetry all the rest of Animalia have bilateral symmetry Distinct head concentration of sensory organs (i.e. eyespots) Promotes active, directional movement • True muscle from mesoderm; all the rest of Animalia have this

Phylum Platyhelminthes: Key features Parasitic flatworms

• Pharynx: for feeding • Example: human pork tapeworm Dissolves food with enzymes, sucks it up! • Gastrovascular cavity is highly branched • Gas exchange via diffusion • Nervous system: simple brain & nerve cords • Simple excretory system: water balance • Some flatworms have penises:  use both for reproduction and food capture!

3 Parastic flatworms Phylum Annelida: “ringed”

• Schistosoma Causes swimmer’s itch Also causes the more severe schistosomiasis

• Schistosomiasis Enabled Taiwan to avoid invasion by Mainland China

Phylum Annelida: Key features Phylum Annelida: Key features

• Tubular gut; one-way • Bilateral symmetry and true muscle. digestive path Specialized regions; more • Segmentation: allows for efficient digestion independent movement of muscles in each segment • ; closed, More effective movement with • : fluid-filled body cavity • Nervous system with brain, paired ventral nerve cords, Hydrostatic skeleton one ganglion per segment Increased surface area for (concentrations of nerve gas exchange cells)

Phylum Annelida diversity Parasitic?

• Other than blood sucking .. Marine Polychaetes None known. Blood leeches can be used medicinally Anticoagulant, stimulates blood circulation in reattachment surgery • But some transmit parasitic Leeches Whirling disease in farmed fish

Earthworms (Photo courtesy of Marietta University)

4 Phylum : Molluscan The “soft-bodied” animals • Shell • Mantle Secretes shell Body covering (non- shelled mollusks)

• Head and assocated sensory structures • Foot and epipodial tentacles

Molluscan body plan Phylum Mollusca: Gastropods

• Radula • Gastropods are one-footed crawlers Toothed tongue-like structure • Examples: snails; sea and landslugs • Gill • Some have no shell (slugs) • Visceral mass: the “guts” • Land snails use their mantle as a kind of “lung” Complete digestive system Open circulatory system • Nervous system with brain, paired ventral nerve cords, some ganglia

Phylum Mollusca: Bivalves Cephalopoda: “Head-footed”

• Bivalves are filter feeders • Cephalopods are marine predators Their gill is used for feeding as well as respiration! • Examples: Nautilus, squid, octopus • Examples: scallops, oysters, mussels and clams • Notable features (a scallop and mussels are shown)  Shell reduced (pen in squid)  Foot gives rise to arms and funnel • They have “lost their heads”  Head with well-developed and beak  Mantle forms thick, protective body covering  Functions in jet propulsion  Chromatophores: rapid, accurate color change  Circulatory system closed!  Nervous system highly developed

5 Phylum Arthropoda: “jointed foot” Phylum Arthropoda: Key features

• dominate the earth: more and more individuals than any other phylum! • • Representative members shown here… Secreted by epidermis Strengthed with What other organisms are strengthened by chitin? Must molt to grow How can an grow larger if it builds its new exoskeleton beneath the old one? Heaviness limits size (on land)

Phylum Arthropoda: Key features Arthropoda: Key features (cont.)

• Paired and jointed appendages • Arthropods have well- Arthropod = “jointed leg” developed sensory • Segmentation (like systems Annelida) Compound eyes Segments organized into body regions (i.e. head, Antennae: chemosensory thorax and abdomen of and tactile ) • NOTE : Other body systems Numerous receptors all over roughly similar to Phylum their bodies that detect light, Annelida and Mollusca odors, pressure, etc… Open circulatory system

Phylum Arthropoda: Insects Phylum Arthropoda: Insects

• Numerous! Three times more species than • Three different types of metamorphosis: all other classes of animals combined!  Hemimetabolous: Nymphs look like small wingless adults • One pair of antennae, compound eyes and 3 pairs of legs.  Holometabolous: larvae  pupae  adult • The only flying invertebrates  Allows for escape from predators and efficient foraging

6 Phylum Arthropoda: Arachnids Phylum Arthropoda: Arachnids

• No compound eyes; no antennae! • Most are predatory meat eaters  have simple eyes (spiders usually have 8)  Spiders have paralyzing and digestive enzymes; dissolve food outside body before sucking it up! • Examples: Spiders Harvestmen (daddy longlegs) Scorpions Sun spiders Whip scorpions , ticks

Phylum Arthropoda: Myriapoda Phylum Arthropoda: Crustaceans

• Myriapods have many legs  Centipedes have 1 pair per segment, millipedes have 2 pairs per • Mostly aquatic segment. • All have one pair of antennae • Two pair of antennae • Most have simple eyes only and compound eyes • Centipedes are always venomous, millipedes are not. • Number of legs varies • Examples: water fleas, pill bugs, crabs &, yes, !

Phylum Echinodermata: Phylum Nematoda: roundworms Spiny-skinned • are everywhere! • Important decomposers: billions in every acre of topsoil! • Like the Arthropoda, they have an exoskeleton with chitin that they molt in to grow. • Some are parasitic  Example: (trichinosis) and worms

7 Body plan: Other aspects Echinodermata: 4 key features • Digestive system • Calcareous internal skeleton Can be highly branched Why considered Complete in some “internal”? • Nervous system • Water vascular system No brain Controls tube feet Branches parallel water vascular system • Symmetry Sensory (sea stars) Bilateral symmetry  spots (larvae) Receptors on tube feet Pentamerous radial • No circulatory system symmetry (adults) • Gas exchange via tube • Mutable connective feet and gills tissue

Sea stars

• Feeding

• Regeneration

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