Zoology: Lab Study Guide

Zoology Lab Study Guide

Sponges (polyphyletic):

Demosponges:

  •  contain some species of freshwater sponges; mostly marine
  •  spicules made of silica
  • skeleton made of protein similar to collagen
  • can be preserved as natural sponges
  • Spongilla sp. (spongilla skeletons)

Calcareous Sponges:

  • spicules made of calcium carbonate
  • Scypha (fingerlike body shape; looks like porous leech)
  • Leucilla sp. (Rhabdodermella)   

 

Cnidaria (diploblastic; ciliated larvae):

Hydrazoans:

  • sex cells formed within the epidermis
  • Hydra
    • exist only in polyp form (no medusa form)
    •  lives in freshwater ponds and streams
    • mesoglia located between ectoderm and endoderm
    • pulls food into mouth with its tenetacles
  • Obelia
    •  exist in polyp (sessile) and medusa (motile) forms
    •  know feeding polyps (like fingers); reproductive polyps
  • Physalia (Portuguese Man-of-War)
    • looks like a jellyfish
    • colonial hydrozoan, made up of polyps and medusas functioning as a
    • single “superorganism”
    • possess long “streamers” loaded with cells that produce stinging
    • hairs called cnidocytes
    • cnidocytes used for defense against predators and to capture prey

Jellyfish (Scyphozoa):

  • sexually reproducing adults are fairly good-sized medusas
  • life cycle is basically the same in both species
  • Aurelia (four leaf clover in the middle)

Corals and Sea Anemones (Anthozoa):

  • exist only in polyp form (no medusa form)
  • sea anemones usually attain fairly good size and exist as solitary types
  • corals are tiny and exist as colonies of individuals (colonial)
  • Sea anemones: square shape with numerous tentacles on the top near the mouth
  • Corals:
    • have dinoflagellate algae living symbiotically within their tissues
    •  found in habitats where there is a small amount of light so the
    • autotrophic algae can produce food for the coral (symbiosis)
    • have radial symmetry
    • separated into stony corals and soft corals
    • Stony corals secrete an exterior “skeleton” made of calcium
    • carbonate (limestone); examples are mushroom coral (formed by single polyp), brain coral and elkhorn coral (formed by colonies of polyps)
    • Soft corals are always colonial and form an internalized skeleton made of protein (often quite colorful); more like synthetic sponge; soft and smooth

Flatworms:

  • vermiform body shape (“worm-like”)
  • long and cylindrical
  • no complete digestive tract
  • bilateral symmetry
  • broken down into three taxa (two are parasitic)
  • Turbellarians:
    • free-living animals
    • Planaria
    • have a ciliated epidermis to propel through water
    • move in a spiral fashion
  • Flukes (Trematoda):
    • As parasites, the animals in this group feed off the tissues and nutrients of their hosts
    • primary host – the host in which the adult parasite lives
    • intermediate host – the host(s) in which larval parasites live
    • Clonorchis sinensis (Chinese Liver Fluke)
      •  parasite resides in the muscle tissue in an adult fish
      •  hermaphrodites
      • can reproduce through self-fertilization or cross-fertilization
    • Schistosoma mansoni (Blood Fluke)
      • cause serious diseases for humans in underdeveloped countries
      • adult blood flukes live as parasites in the blood vessels of primary hosts (humans)
      • not hermaphrodites like liver flukes
      • dioecious- separate male and female worms

Tapeworms (Cestoda):

  • parasites (like flukes)
  •  NO GUT and NO MOUTH (evolutionary reversal)
  • body consists of many segments (proglottids)
  • head structure called a scolex
  • each segments develops its own set of male and female reproductive parts which mature and become functional
  • immature segments near the head; mature segments near the rear
  • mature segments contain fertilized eggs (gravid = pregnant)
  • typically live in animal’s digestive system
  • Dipylidium caninum (infects dogs)
  • Taenia pisiformis

Annelids (segmented):

  • Polychaetes (means “many setae”):
  • many setae project from the epidermis of the body
  • Neanthes virens (“clamworm” or “sandworm”)
  • segmented body with fingerlike parapodia
  • setae at the end of parapodia

Earthworms and Leeches (Clitellates):

  • share a common feature called a clitellum, which functions in reproduction (looks like a bandage)
  • clitellum contains reproductive organs; houses eggs and sperm
  • Lumbricus terrestris (common earthworm)
    • contain a coelom and hydrostatic skeleton
    • squeeze circular muscles and lengthen longitudinal muscles to move
    • circular muscle located on outside ring in cross section
    • longitudinal muscle rippled perpendicular (smaller diameter)
    • move in coordinated fashion; one part then next part…etc.
    • two ends move in conjunction
    • hermaphrodites
  • Leeches
    • primarily found in water
    • either predators or external parasites
    •  unsegmented ceolom; continuous body cavity; hydrostatic skeleton
    • suckers on posterior and anterior ends
    • two ends move independently

Mollusks:

  • share a body structure consisting of a:
  • muscular foot (movement)
  • visceral mass  that contains all of the internal organs
  • fleshy mantle that covers the visceral mass and in which is found a cavity where gas exchange via gills occurs
  • Clams, Oysters, Mussels (Bivalves):
    • bivalves = two-part shell
    • flattened laterally
    • mostly sessile as adults
    • obtain food by “ciliary filter feeding” (“suspension feeding”)
    • little nervous system and no brain
    • major muscles function to open and close the shell
  • Long-necked clams
    • contain incurrent and excurrent siphons
    • excurrent siphon is closest to the hinge of the shell
    • control water flow for ciliary filter feeding
  • Mussels
    • have long byssal threads that attach to substrates
  • Scallops
    • one of few types of bivalves that can swim as adults
    • clap its valves together to create a jet of water
    • enlarged adductors muscles permit movement (dark line)
  • Chitons:
    • flattened dorso-ventrally (unlike bivalves)
    • broad muscular foot
    • most scrape bacteria, algae, and protists from the rocks
    • contain 8 dorsal plates
    • thick mantle below dorsal plates
    • gills on underside of mantle
    • mouth on the ventral surfaces or foot
  • Snails and Slugs (Gastropods):
    • gastropod refers to the large muscular foot found on ventral surface (“gastro” = stomach; “-pod” = foot)
    • most possess a coiled shell; slugs lack one
    • snails can retract their entire body into the shell for defense
    • not all shelled gastropods are capable of complete retraction
    • land slugs and sea slugs contain four sensory tentacles and a large
    • muscular foot
  • Squid, Octopus, Cuttlefish (Cephalopods):
    • big head (“cephalon-“) with feet (‘-pod”)
    • fast moving predators with large brains and well-developed sensory
    • organs
    • shells are much reduced or absent in most cephalopods
  • Squid 
    • tentacles have pointy ends; arms have v-shape ends
    • funnel (siphon) located on ventral side near collar to right
    • siphon ejects water quickly (jet propulsion) – permits rapid movement

Nematodes (Roundworms):

  • complete digestive tract consisting of a mouth, body cavity, and anus
  • possess an exoskeleton
  • dioecious – separate male/female worms
  • Ascaris lumbricoides
    • parasitic nematode whose hosts are pigs and humans
    • very long (live in intestines of host); yellowish
    • males have spicules on anal end; females do not
  • elegans
    • common model organism
    • thicker worm; move by slow slither
  • Vinegar eel
    • small worms that can survive in very acidic environments (low pH)
    • move chaotically in a rapid, sperm-like motion

Arthropods:

  • greatest number of species
  • exoskeleton; segmentation; jointed appendages
  • Chelicerates:
    • Horseshoe Crab (Limulus polyphemus)
    • chelicerae located at end opposite the head
  • Arachnids:
    • Spiders
      • cephalothorax = head; abdomen = body segment
      • chelicerae contain the fangs
      • pedipalps = limbs near the mouth
      • In male spiders, pedipalps are responsible for sperm transfer
      • webmaking spinnerets located at anus (posterior end)
    • Scorpions
      • cephalothorax (head); chelicerae (fangs); pedipalps (limbs near face)
      • stinger used to transfer venom to immobilize prey
  • Crustaceans:
    • Crayfish
      • serial homology – similarity in form among segments but with modifications for different functions within the species
      • simple organization of repeating units, parts of each unit modified to fit the animals needs
      • antennae and short antennae (antennules)
      • mandibles = mouth parts with a toothed edge
      • large claws (chelipeds)
      • 4 pairs of walking legs
      • swimmerets on all but last abdominal segment
      • uropods = side of tail fan
      • appendages are jointed; two branches (exopod/endopod)
      • Barnacles are crustaceans (not mollusks) because they possess segmentation.
  • Myriapods:
    • Centipedes (carnivores)
      • 2 appendages per segment
      • oval cross section
      • fast speed
    • Millipedes (herbivores)
      • 4 appendages per segment
      • circular cross section
      • slower speed
  • Hexapods (Insects and their relatives):
    • most diverse class; more total species than all other groups combine
    • most dominant group in the world today
    • Basic Hexapod Anatomy:
      • Eastern Lubber grasshopper (Romalea microptera)
        • three body regions: head, thorax, abdomen
        • single pair of antennae
        • three pairs of jointed legs
    • Insect Metamorphosis:
      • all insects lay eggs
      • must molt the exoskeleton in order to grow
      • changes in size and form during life cycle = metamorphosis
      • Incomplete Metamorphosis – larval stage looks just like adult
        • young hatch without fully developed wings and without the ability to reproduce
        • most obtain wings after last                                                          *grasshopper and cockroach
      • Complete Metamorphosis – larval stage looks very different
      • young hatch as wingless, worm-like larva
      • grow in size with each molting
      • pupa phase = body structure changes from larval to adult form* Japanese beetle, butterfly, paper wasp, mosquito

Echinoderms (spiny skin; radial symmetry):

Sea Stars:

  • pyloric caeca (digestive glands) = long branches running down one arm
  • stomach = broken in two large rings with a cross-shape over top (center)
  • mouth and tube feet on the ventral surface
  • ampulla = bulb like structure on top of the tube foot (creates suction)
  • water vascular system consists of radial canals, ring canal, stone canal, a madreporite
  • the radial canal extends along the arms; the ring canal is central; the stone
  • canal is along the ring canal adjacent to the madreporite
  • locomotion = water is pushed through the radial canal and expelled out of madreporite on the dorsal surface and tube feet on the ventral surface

Sea urchins and Sand dollars:

  • sea urchins have a calcium carbonate jaw that make up the animals
  • mouthparts (known as Aristotle’s lantern); located in the center of the ventral surface (white circle)
  • female gonad (carries eggs) = little sac located on interior next to madreporite
  • sand dollars look like they have a 5-leaf clover on top of them; cookie cutter

Sea cucumbers:

  • shaped like a large bean with brushy tentacles coming out of the top

 

Chordates (segmented): *Cephalochordates are the only invertebrates

  • notochord (becomes jellylike substance found in intervertebral discs)
  • dorsal, hollow neural tube (becomes brain and spinal cord)
  • pharyngeal slits
  • post-anal tail
  • these features form during early embryonic development, but do not necessarily
  • persist throughout a chordate’s life
  • Cephalochordates (invertebrates):
    • Lancelets (Amphioxious sp) are the closest relatives to vertebrates
    •  looks like a worm but possesses a dorsal hollow neural tube and notochord
  • Jawless Fish (polyphyletic group):
    • hagfish = have a skull but no vertebrae
    • lampreys = have skull and vertebrae
    • head, nostril (looks like an eye), mouth, anterior/posterior dorsal fin
    • caudal fin on tail end
    • share an absence of paired fins
    • close evolutionary relationship to cephalochordates
  • Cartilaginous Fish (Chondrichthyes):
    • includes sharks, skates, and rays
    • predators (jaws); have eyes
    • multiple gill slits (5-7)
    • skates and rays possess dorso-ventral flatness (bottom-dwellers) with a jaw on the
    • ventral side of the animal (crush mollusks and other invertebrates on ocean floor)
  • Ray-finned Fish (Osteichthyes)(bony fish):
    • also contain flounder, eel, seahorse
    • have eyes and nostril
    • operculum (gill cover); paired pelvic and pectoral fins; lateral line
    • anal fin (ventral); dorsal fin; caudal fin (tail)
      • Tetrapods
        • two pairs of limbs rather than fins
        • ex. coelacanth
  • Amphibians (cold-blooded):
    • first terrestrial deuterostomes were probably salamander-like amphibians
    • most adults have the ability to live on land
    • most have gills; smooth skin for gas exchange (dissolved gases in water)
    • most have four limbs
    • caecilian demonstrates the evolutionary phenomena of reversal and convergence
      • reversal = no limbs
      • convergent with the snake
  • Reptiles (polyphyletic group; cold-blooded):
    • only way to encompass all reptiles in a single phylogenetic group is with birds
    • scaly skin (protection, temperature regulation, prevent desiccation)
    • most have lungs
    • lay eggs on land (amniotic egg)
    • caiman is a relative of alligators and crocodiles
    • turtle has a horny shell made up of larger plates called scutes (not scaly)
    • * “horned” toad = lizard; not a true toad or frog (only resemblance is mouth)
  • Birds (Aves):
    • one of many reptile groups; closest living relatives of dinosaurs
    • teeth and long tail region of the vertebral column (not found in dinosaurs)
    • feathers and beak; have esophagus, two-chambered stomach, and intestines
    • warm-blooded
  • Mammals:
    • hair, mammary glands, fleshy outer ears
    • platypus lays eggs (reversal = no ears)
    • placental mammals = carry young in the uterus
    • marsupial mammals = carry young inside pouch

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