Invertebrate Biology Notes PDF

Invertebrates Notes #1: Kingdom Animalia: Invertebrates Notes #2: Phylum Porifera (sponges) Notes #3: Phylum Cnidaria (cnidarians) Notes #4: Phylum Platyhelminthes (flatworms) Notes #5: Phylum Nematoda (roundworms) Notes #6: Phylum Annelida (segmented worms) Notes #7: Phylum Mol...

Invertebrates Notes #1: Kingdom Animalia: Invertebrates Notes #2: Phylum Porifera (sponges) Notes #3: Phylum Cnidaria (cnidarians) Notes #4: Phylum Platyhelminthes (flatworms) Notes #5: Phylum Nematoda (roundworms) Notes #6: Phylum Annelida (segmented worms) Notes #7: Phylum Mollusca (mollusks) Notes #8: Phylum Arthropoda (arthropods) Notes #9: Phylum Echinodermata (echinoderms) Notes #10: Invertebrate Systems #1) Kingdom Animalia: Invertebrates  Kingdom Animalia Characteristics of animals: eukaryotic cells; lack cell walls multicellular heterotrophic two groups: 1) Invertebrates (no backbone) 2) Vertebrates (backbone)  Invertebrate Phyla There are 8 invertebrate phyla: 1) Phylum Porifera (sponges) 2) Phylum Cnidaria (cnidarians) 3) Phylum Platyhelminthes (flatworms) 4) Phylum Nematoda (roundworms) 5) Phylum Annelida (segmented worms) 6) Phylum Mollusca (mollusks) 7) Phylum Arthropoda (arthropods) 8) Phylum Echinodermata (echinoderms)  Trends in Animal Evolution Important trends in animal evolution: 1) Cell Specialization 2) Early Development 3) Body Symmetry 4) Cephalization 5) Body Cavity (coelom) 1) Cell Specialization All the different cell types are derived from 3 germ layers: 1) Ectoderm – outer layer 2) Mesoderm – middle layer 3) Endoderm – inner layer 2) Early Development In protostomes the blastopore becomes the mouth (most invertebrates) In deuterostomes the blastopore becomes the anus (echinoderms and vertebrates only) Cladogram showing deuterostome evolution  3) Body Symmetry Asymmetry – no plane of symmetry Radial symmetry – multiple planes of symmetry Bilateral symmetry – one plane of symmetry  4) Cephalization Cephalization – the evolutionary trend towards a concentration of nerves and sensory organs in the anterior (head)  5) Body Cavity The coelom is a fluid-filled body cavity that contains the internal organs. The three stages in the evolution of a body cavity: 1) Acoelom → 2) Pseudocoelom → 3) Coelom  Acoelom Acoelom: no body cavity three germ layers stacked; no space e.g. flatworm  Pseudocoelom Pseudocoelom: “false” body cavity partially lined by mesoderm e.g. roundworm  Coelom Coelom: full body cavity completely lined by mesoderm e.g. annelid #2) Phylum Porifera (sponges)  Phylum Porifera (sponges) Characteristics: Sponge body plan Latin “poros” = passage germ layers: none filter feeders (use collar cells to body cavity: absent trap food particles) body symmetry: asymmetric endoskeleton made of spongin cephalization: absent and/or spicules of calcium carbonate or silica amoeboid cells build spicules and help digest food  Sponges – Examples Venus’ flower basket Bath sponge Tube sponge  Anatomy of a Sponge – water flow Water flow: pore (ostia) → central cavity → osculum #3) Phylum Cnidaria (cnidarians) Class Hydrozoa Class Scyphozoa Class Anthozoa  Phylum Cnidaria (cnidarians) Characteristics: Cnidarian body plan Latin “cnidaria” = nettles cell layers: two mostly carnivorous body cavity: absent tentacles bear stinging body symmetry: radial nematocysts cephalization: absent alternate between polyp and medusa body forms gastrovascular cavity (GVC) hydrostatic skeleton  Body Forms: Polyp vs Medusa Polyp – flower-like form; Medusa – bell-shaped form; sessile (=attached to bottom) free-swimming Stinging Cells (cnidocytes) of the Tentacles A stinging nematocyst is ejected from a cnidocyte cell when triggered It immobilizes prey  Class Hydrozoa Hydra Portuguese Man-of-War  Class Scyphozoa Lion’s Mane Jellyfish Moon Jelly Sea Wasp  Class Anthozoa Reef Coral Sea Anemone Sea Pen Sea Fan #4) Phylum Platyhelminthes (flatworms) Class Turbellaria Class Trematoda Class Cestoda  Phylum Platyhelminthes (flatworms) Characteristics: Flatworm body plan Latin “platy” = flat, germ layers: three “helminth” = worm body cavity: acoelom unsegmented body symmetry: bilateral free-living or parasitic cephalization: present hydrostatic skeleton  Class Turbellaria (turbellarians) Characteristics: free-living carnivores and scavengers live in fresh, salt water, or on land move with cilia marine turbellarian Planaria GVC example: Planaria, marine turbellarians  Anatomy of Planaria One-opening digestive tract: Flames cells excrete excess mouth → pharynx → GVC water  Class Trematoda (flukes) Characteristics: parasitic infect blood and organs life cycle typically involves more than one host: primary host – sexual reproduction occurs intermediate/secondary host – asexual rep. occurs examples: blood flukes (e.g. Schistosoma and liver fluke swimmer’s itch) and liver flukes Schistosoma Life Cycle (sequence the stages)  Class Cestoda (tapeworms) Characteristics: internal parasites lack digestive tract body composed of many repeating sections called proglottids (contain eggs) the scolex (head) attaches to host’s tapeworm intestines example: tapeworm  Anatomy of a Tapeworm Tapeworm infection occurs by ingesting infected meat (with larval cysts) #5) Phylum Nematoda (roundworms)  Phylum Nematoda (roundworms) Characteristics: Roundworm body plan Latin “nemato” = thread germ layers: three unsegmented body cavity: pseudocoelom digestive system has two body symmetry: bilateral openings – a mouth and an anus cephalization: present hydrostatic skeleton examples: free-living or parasites  Nematode Digestive System The two-opening digestive system: (the first phylum to have this) mouth → pharynx→ intestine → anus  Adult Ascarid Worm Ascarid infection occurs through ingesting food or water containing Ascarid eggs Ascarid Worm Lifecycle (sequence the stages)  Trichinella Trichinella infection occurs from consuming raw pork  Eye Worm Eye worm is transmitted through the bite of a fly #6) Phylum Annelida (segmented worms) Class Polychaeta Class Oligochaeta Class Hirudinea  Phylum Annelida (segmented worms) Characteristics: Annelid body plan Latin “annellus” = little ring germ layers: three body composed of segments body cavity: coelom separated by internal body symmetry: bilateral partitions cephalization: present digestive system has two openings closed circulatory system* respiration by diffusion across skin hydrostatic skeleton  Class Polychaeta (polychaetes) Characteristics: most live in salt water pair of bristly, fleshy appendages on each segment sandworm examples: sandworm, fanworm fanworm  Class Oligochaeta (oligochaetes) Characteristics: lack appendages few bristles terrestrial or fresh water earthworm examples: Tubifex (sludge worm) , earthworm Tubifex  Earthworm Systems e.g. Nephridia are kidney-like structures that excrete nitrogenous wastes  Earthworm Digestive System mouth → pharynx → esophagus → crop → gizzard → intestine → anus  Class Hirudinea (leeches) Characteristics: lack appendages carnivores or blood-sucking external parasites most live in fresh water example: medicinal leech leech #7) Phylum Mollusca (mollusks) Class Bivalvia Class Gastropoda Class Cephalopoda  Phylum Mollusca (mollusks) Characteristics: Mollusk body plan Latin “molluscus” = soft germ layers: three four body parts: body cavity: coelom 1) foot body symmetry: bilateral 2) shell (endo- or exoskeleton) cephalization: present 3) mantle 4) visceral mass digestive system with two openings Four Body Parts of a Mollusk (text pg. 586)  Class Bivalvia Characteristics: two-part hinged shell wedge-shaped foot clam oyster typically sessile as adults some burrow in mud or sand examples: clam, oyster, scallop, mussel scallop mussel  Class Gastropoda (gastropods) Characteristics: use broad, muscular foot in movement most have spiral, chambered snail slug shells; some lack shell distinct head aquatic or terrestrial examples: snail, slug, nudibranch, limpet nudibranch limpet  Class Cephalopoda (cephalopods) Characteristics: foot is divided into tentacles closed circulatory system* examples: octopus, squid, octopus squid nautilus, cuttlefish nautilus cuttlefish Squid Anatomy #8) Phylum Arthropoda (arthropods) Subphylum Trilobita Subphylum Chelicerata Subphylum Uniramia Subphylum Crustacea  Phylum Arthropoda (arthropods) Characteristics: Arthropod body plan Latin “arthro” = jointed, germ layers: three “poda” = foot body cavity: coelom exoskeleton of chitin body symmetry: bilateral jointed appendages cephalization: present segmented body many undergo metamorphosis during development open circulatory system*  Subphylum Trilobita (trilobites) Characteristics: all extinct (known from fossil record) each appendage divided into a gill and a walking leg trilobite  Subphylum Chelicerata (chelicerates) Characteristics: mouth parts: chelicerae (1st pair) – used for biting or sucking horseshoe crab tick mite pedipalps (2nd pair) – used for prey capture two-part body – cephalothorax and abdomen lack antennae spider tarantula scorpion examples: horseshoe crab, tick, mite, spider, tarantula, scorpion Chelicerate Body (e.g. spider)  Subphylum Uniramia Characteristics of uniramians: almost all terrestrial one pair of antennae mandibles examples: centipedes, millipedes, insects  Centipedes (Class Chilopoda) Characteristics: long body consisting of many segments one pair of legs per segment poison claws for feeding carnivorous centipede  Millipedes (Class Diplopoda) Characteristics: long body consisting of many segments two pair of legs per segment mostly herbivorous millipede  Insects (Class Insecta) Characteristics: body divided into three parts – head, thorax, abdomen three pairs of legs one or two pairs of wings some undergo complete metamorphosis (e.g. butterfly) Insect – Three Part Body  Grasshopper Systems e.g. Malpighian tubules are kidney-like structures that excrete nitrogenous wastes  Grasshopper Respiratory System Oxygen enters through tiny spiracles and into tracheal tubes where it diffuses directly to tissues.  Insect Metamorphosis Complete metamorphosis: Incomplete metamorphosis:  Symbiosis in Arthropods Symbiosis is a close relationship between two species Three types: 1) mutualism – both organisms benefit 2) commensalism – one organism benefits, the other neither benefits nor is harmed 3) parasitism – one organism harms the other  1) Mutualism Aphids feed the ants and the ants protect the aphids  2) Commensalism Pseudoscorpions hitch a ride by grabbing hold of flying insects  3) Parasitism Parasitic wasps inject their eggs into a host (e.g. moth larvae)  Subphylum Crustacea most are aquatic; salt water two pair of antennae barnacle crayfish pill bug mouth parts called mandibles carapace covers body e.g. crab, crayfish, pill water flea crab bug, water flea, barnacle #9) Phylum Echinodermata (echinoderms)  Phylum Echinodermata (echinoderms) Characteristics: Echinoderm body plan Latin “echino” = spiny, germ layers: three “dermata” = skin body cavity: coelom deuterostomes body symmetry: radial water vascular system cephalization: absent respiration across skin gills endoskeleton  Sea Lilies and Feather Stars Characteristics: filter feeders feathery arms for feeding and respiration examples: sea lily, feather star sea lily feather star  Sea Stars Characteristics: star-shaped carnivorous bottom dwellers sea star mouth on lower surface, anus on top surface examples: crown-of thorns, sea star, sunstar crown-of-thorns sunstar  Water Vascular System of Sea stars madreporite → stone canal → ring canal → radial canal → ampulla → tube feet  Brittle Stars and Basket Stars Characteristics: small body disk most have only five arms lack an anus brittle star most are filter feeders or detritus feeders examples: brittle stars and basket stars basket star  Sea Urchins and Sand Dollars Characteristics: lack arms body encased in rigid, box-like covering covered with spines sea urchin most grazing herbivores or detritus feeders examples: sea urchin, sand dollar sand dollar  Sea Cucumbers Characteristics: leathery, cylindrical body with feeding tentacles on one end mostly detritus or filter feeders endoskeleton greatly sea cucumber reduced #10) Invertebrate Systems  Invertebrate Systems Six major invertebrate systems: 1) skeletal system 2) digestive system 3) circulatory system 4) respiratory system 5) excretory system 6) nervous system  Skeletal System exoskeleton endoskeleton hydrostatic skeleton Digestive System Circulatory System Respiratory System Excretory System Nervous System