Invertebrate Diversity Comparison of Increasing Complexity What is
Invertebrate Diversity Comparison of Increasing Complexity
What is an invertebrate? Name some common invertebrates? Are snakes invertebrates?
Introductory Vocabulary Invertebrate – animal without a backbone Coelom – fluid-filled space between body wall and intestine Cephalization – sensory organs concentrated at the anterior end of the organism Sexual reproduction – gametes are produced and fuse to form unique diploid offspring Asexual reproduction – single parent produces offspring genetically identical to itself Hermaphrodite – animals with both ovaries and testes
Sessile – nonmotile; animal that doesn’t move on its own Open circulatory system – vessels empty into body spaces called sinuses Closed circulatory system – blood never leaves vessels as it flows through the body Compound eye – eye with many lenses; found in arthropods Notochord – stiff rod found in chordates that becomes the vertebral column in vertebrates Dorsal nerve cord – bundle of nervous tissue found in chordates that becomes the spinal cord in vertebrates Pharyngeal slits – openings in the pharynx found in chordates that give rise to many structures in vertebrates
Kingdom Animalia Invertebrate phyla: Porifera -sponges Cnidaria-sea anemones, coral and jelly fish Platyhelminthes-flatworms (planaria, flukes, tapeworms) Nematoda -roundworms
Mollusca-slugs, snails, “seashell animals”, octopii and squid Annelida – segmented worms (marine worms, earthworms & leeches) Arthropoda – insects, arachnids & crustaceans Echinodermata – starfish, sand dollars, sea urchins, & sea cucumbers
• Sponges Porifera – Multicellular; no true tissues; asymmetric; sessile – spongin- protein fibers for structure; spicules for skeleton – individual cells acting together as an organism • filter feeders using collar cells (choanocytes) & amoebocytes • Water enters pores and exits osculum – Asexual reproduction • fragmentation – sexual reproduction (hermaphroditic) • External fertilization
• • Classes of cniderians: Hydrozoa – hydra, Obelia, & Portuguese man-of-war Scyphozoa – jellyfish Anthozoa – sea anemones & coral Cnideria Radial symmetry; true tissues; sessile and/or motile Cnidocytes - stinging barbs to capture prey Tentacles to bring prey into gastrovascular cavity Two body forms – Polyp – sessile with mouth dorsal – Medusa – motile with mouth ventral • Asexual reproduction - budding • Sexual reproduction - external fertilization resulting in planulae larvae
Platyhelminthes - flatworms -bilateral symmetry; cephalization; acoelomate; organs -Nervous system: ganglia & nerve cords -Excretory system: flame cells -Digestive system: two-way digestive tract with common mouth/anus; gastrovascular cavity -Respiratory system: diffusion through epidermis -Circulatory system: none (diffusion) -Reproductive system: -Sexual – internal fertilization; hermaphroditic; lay eggs -Asexual - fragmentation
Class Trematoda Class Turbellaria - planaria - freeliving - one of few freshwater species “typical” flatworm Class Cestoda • Tapeworms • Parasites • Attach to intestinal wall of host with scolex • proglottids – segments packed with reproductive organs • absorb nutrition from host –don’t need digestive system - endoparasites OR ectoparasites - complex life cycle with more than one host - primitive or no digestive system Schistosoma – major public health threat; cause liver
Phylum Nematoda - roundworms - pseudocoelomate - hydrostatic skeleton - one-way digestive system with separate mouth/anus - Respiration and circulation by diffusion - Have longitudinal muscles - Reproduction – sexual; complex life-cycle with multiple hosts - Most are free-living predators in the soil - Some are parasitic; hookworms, pinworms, Trichinella
Mollusca Classes of mollusks – based on body plan: *Gastropoda – stomach-foot; snails and slugs *Bivalvia – two-shells; clams, oysters, mussels *Cephalopoda – head-foot; nautilus, squid, octopi, cuttlefish • Coelomate; bilateral symmetry; organs; exoskeleton (shell) • 3 -part body plan: – Visceral mass – contains organs – Mantle – secretes shell – Foot – locomotion • Radula – for feeding • cephalization • Open circulatory system • One-way digestive system • Nephridia – excretory organs • Respiration – gills, mantle cavity, and/or diffusion across skin • Reproduce sexually; many hermaphroditic; form trochophore larvae
ANNELIDA • Oligochaeta – earthworms • Hirudinea – leeches • Polychaeta – marine worms
Major characteristics of all annelids: • Segmentation – separated by septa; each segment has organs of each major system • Cephalization – including cerebral ganglia • Ventral nerve cord • Coelom – hydrostatic skeleton • Organ systems • Setae – bristles for movement • Parapodia – fleshy appendages for movement &/or respiration
Earthworms • Ecologically important scavengers • Two layers of muscle: longitudinal & circular • 5 hearts; closed circulatory system • Nephridia for excretion • Respiration through epidermis • Complex digestive system with mouth, pharynx, esophagus, crop, gizzard, intestine, and anus • Sexual reproduction; hermaphroditic; clitellum forms mucus cocoon to protect fertilized eggs
How are HUMANS separated into body segments? • Remnants of segmentation are visible in the embryo as repeated blocks of tissue called somites and in the vertebral column
Arthropods • largest and most diverse phylum; includes insects, crustaceans, spiders • segmented bodies – head, thorax, & abdomen or cephalothorax & abdomen; segmentation apparent on abdomen • jointed appendages (3, 4 or 5 pairs of walking legs plus assorted other specialized appendages) • Respiration: spiracles into trachea; gills; book lungs • Excretion through Malpighian tubules • Incomplete or complete metamorphosis • exoskeleton of chitin *complex muscular system • ventral nerve cord & brain * open circulatory system • compound eyes * ecdysis (molting)
Millipedes – 2 pairs of legs per segment - herbivores or detritovores, but can be really smelly! - one pair of antennae Centipedes – 1 pair of legs - predators with jaws - one pair of antennae per segment
Insects – 3 body regions: head, thorax, abdomen - 3 pairs of legs attached to thorax - exoskeleton of chitin - jaws (mandibles)modified for particular feeding method - wings are extensions of the exoskeleton; 0, 1 or 2 pairs - 1 pair of antennae - compound eyes
Arachnids – spiders, scorpions, ticks, & mites • Chelicerae – mouthparts modified into pincers or fangs • Cephalothorax & abdomen • 4 pairs of walking legs • No antennae • Simple eyes tick • Spinnerets & silk glands in spiders • Book lungs in spiders • Predators that consume liquified food • Distantly related to horseshoe crabs mite
Crustaceans Ecologically important – copepods & krill are planktonic crustaceans that form the basis of many marine food chains Crabs, lobsters, shrimp, & crayfish are other well-known crustaceans called decapods – “ 10 feet” First pair of walking legs often modified into chelipeds (pincers) 2 pair of antennae Compound eyes Sexual reproduction Cephalothorax covered by carapace Small appendages on abdomen of of some called swimmerets Barnacles are sessile crustaceans Pill bugs (isopods) are terrestrial crustaceans with gills
• Only live in salt water (oceans) ECHINODERMS • Five-part radial symmetry in adults; larvae are bilaterally symmetrical • Hard, bumpy, spiny endoskeleton composed of ossicles • Water vascular system with 5 rows of tube feet that aid them in movement, gas exchange, food capture and waste excretion. • Skin gills increase respiratory surface area & function in excretion • Feeding in starfish involves everting stomach out of mouth, digesting prey outside of body, and then pulling the digested material into the body; other echinoderms tend to be filter feeds or detritivores Ex: starfish, sand dollar, sea cucumber, sea urchin, sea cucumber, sea biscuit, brittle stars, sea lilies, sea daisies, sea pens, feather stars
Invertebrate Chordates 4 characteristics of all chordates: *Notochord tunicate *Dorsal hollow nerve cord *Pharyngeal gill slits *Postanal tail lancelet Invertebrate chordates include tunicates & lancelets; all other chordates are vertebrates
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