ch. 33.txt

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ch. 33.txt
2011-11-28 23:57:02
invertebrates chapter 33 biology 101

Invertebrates, chapter 33, biology 101
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  1. Invertebrates
    • -lack backbone
    • -95% of known animal species
    • -adapted to many environments, which led to great diversity
    • -great variation in size
  2. Porifera
    -5,500 species
  3. sponges
    • -sessile animals that lack tissue = basal animal (lineage originates near root of phyla tree)
    • -live as suspension feeders = trapping particles that travel through its body
  4. spongocoel
    -central body cavity
  5. osculum
    • water flows in and out of this large opening
    • -have folded body walls
    • -some have many oscula and branched water canals
    • -lining of the interior spongocoel are flagellated choanocytes or collar cells
    • -engulf food by phagocytosis
    • -similarities between choanoflagellates and these cells suggest that animals evolved from a choanoflagellate-like ancestor
  6. mesohyl
    • gelatinous region that separates the two layers of cells in the body of the sponge
    • -both cell layers are in water, so gas exchange and waste goes out by diffusion
  7. amoebocytes
    • cells that use pseudopodia
    • -move through mesohyl
    • -take up food from choanocytes, digest it, and send nutrients around the sponge
    • -manufacture tough skeletal fibers within the mesohyl
    • -some sponges have sharp spicules made from calcium carbonate and silica
    • -some produce flexible fibers composed of a protein called spongin
    • -capable of becoming other types of sponge cells, makes sponges incredibly flexible enabling it to adjust its shape to environmental changes
  8. hermaphrodites
    • have both sexes for reproduction; sponges have sequential hermaphroditism
    • -gametes arise from choanocytes or amoebocytes
    • -eggs are in mesohyl
    • -sperm get carried by water current
    • -fertilization in mesohyl
    • -zygote = flagellated larvae; swim from parent
    • -produce antibiotics and defense compounds
    • -cribrostatin can kill penicillin-resistant strain of the bacteria Strep
  9. Cnidarians
    • -Eumetozoans- animals with true tissue
    • -oldest lineage
    • -simple, diploblastic, radial body plans
    • -sac with gastrovascular cavity = central digestive compartment
    • -single opening that functions as mouth and anus
  10. polyp
    cylindrical forms that adhere to substrate by the aboral end; tentacles that extend to catch prey
  11. medusa
    • flattened, mouth-down version of the polyp; move by drifting or undulating
    • -carnivores; use tentacles to catch prey and push into gastrovascular cavity and digest
    • -enzymes break down the food, cells lining the cavity absorb the nutrients
    • -undigested remains get expelled through mouth/anus
  12. cnidocytes
    • cells that function in defense that contain cnidae which are organelles that explode
    • -nematocysts = stinging thread that can penetrate the body wall of the prey
    • -gastrovascular cavity acts like a hydrostatic skeleton for the contractile cells
    • -the volume of the body doesn't change, but the cells contract to change the shape
    • -no brain; nerves react by stimuli
  13. Hydrozoans
    • -alternate from polyp stage to medusa
    • -Obelia life cycle
    • -colony of interconnected polyps (2n)
    • -polyp specialized for reproduction produce medusa by asexual budding (2n)
    • -medusa swim and reproduce sexually (2n)
    • -meiosis ---> egg & sperm meet (n) ---> fertilization ---> zygote (2n) ---> larvae--->polyp
    • -hydras are only ones that only stay in polyp stage
    • -favorable conditions: asexual budding
    • -unfavorable conditions: sexual reproduction ---> resistant dormant zygotes
  14. Scyphozoans
    • -medusa is dominant stage; small polyps
    • -jellies
  15. Cubozoans
    • -cube like shape
    • -complex eyes in fringe of medusa
    • -swim faster than scyphozoans
    • -toxic cnidocytes that can be fatal ---> sea wasps
    • -turtles are resistant to toxin
  16. Anthozoans
    • -sea anemones (only polyp stage)
    • -corals
    • -symbiotic relationship with algae
    • -hard exoskeleton from calcium carbonate
    • -each polyp generation builds on each other, hence rock-like
    • -form huge colonies
    • -pollution, overfishing, and global warming are current threats
  17. Lophotrochozoans
    • -bilateral, triploblastic, 2 openings for mouth and anus, coelom
    • -lophophre = crown of ciliated tentacles used for feeding
    • -trochophore larvae
    • -most diverse
  18. Flatworms
    • -flattened bodies, triploblastic, acoelomates
    • -gas exchange and elimination of waste happens through diffusion
    • -protonephridia = excretory apparatus that maintains osmotic balance with surroundings
    • -network of tubules with ciliated structures called flame bulbs that pull fluid through ducts
  19. Catenulida
    • -100 species
    • -reproduce asexually by budding posterior end
    • -offspring produce own buds while being attached to parent, hence "chain worm"
  20. Rhabditophora
    • -free-living = planarians (Dugesia)
    • -prey on smaller animals and feed on dead ones
    • -cilia on surface glides along a film of mucus they secrete; undulated swimming
    • -eyespots, lateral flaps for detecting certain chemicals, centralized nervous system
    • -asexual reproduction through fission
    • -sexual reproduction b/c they are hermaphrodites
    • -parasites
    • -live in or on host
    • -suckers that attach to organs
    • -tough covering helps protect them from their host
  21. -trematodes
    • -need to leave larvae in host to grow
    • -human parasites live in snails
    • -blood flukes - suffer from schistosomiasis
    • -evades human immunity by mimicking surface proteins, camouflage
    • -manipulates host into tolerating its existence
  22. -tapeworms
    • -live in intestines of animals
    • -anterior end, scolex, is armed with suckers and hooks for attaching to lining
    • -no mouth, no gastrovascular cavity, absorb nutrients from intestine
    • -long ribbon on posterior end called proglottids - little sacs of sex organs
    • -release thousands of fertilized eggs into feces
    • -can get it by eating undercooked pork (intermediate host for larvae)
  23. Rotifers
    • -have alimentary canal = a digestive tube with two openings, a mouth and anus
    • -internal organs lie in pseudocoelom
    • -fluid in pseudocoelom acts as a hydrostatic skeleton
    • -crown of cilia at the mouth, pharynx has jaws called trophi
    • -only females produce females = parthenogenesis
    • -under certain conditions they can reproduce sexually with male and female, but male doesn't feed- only purpose is to mate---> resistant embryos
    • -bdelloidea = they have been around for 100 million years, asexual reproduction did not i ncrease mutations to manifest extinction *puzzling
  24. Lophorphorates
    -have lophophores, U-shaped alimentary canal, no head (sessile), have a true coelom lined by mesoderm
  25. Ectoprocts
    colonial animals encased in exoskeleton, studded with pores; reef builders
  26. Brachiopods
    • lamp shells, with dorsal and ventral side (not lateral like in clams)
    • -only marine
    • -Liingla are nearly identical to fossils of species that lived 400 mya
  27. Molluscs
    • -2nd most diverse phylum
    • -coelomates with:
    • -muscular foot = used for movement
    • -visceral mass = containing the organs
    • -mantle = a fold of tissue that drapes over visceral mass and secretes a shell
    • -mantle cavity = houses gills, anus, and excretory pores
    • -feed by strap like organs = radula
    • -ciliated larval stage, the trochophore
    • -anatomy of mollusk:
    • -nephridium = excretory organ that removes metabolic waste
    • -have an open circulatory system
    • -long coiled digestive tract
    • -nervous system ring around the esophagus
  28. Chitons
    • -oval shaped body with 8 dorsal plates
    • -unsegmented body
    • -suction cup foot
    • -eat algae with radula
  29. Gastropods
    • -snails and slugs
    • -have torsion = as a gastropod embryo develops, its visceral mass rotates up to 180 degrees, causing the animal's anus and mantle cavity to wind up above its head
    • -single, spiraled shell; eye at the end of tentacles; move by cilia and leave slime
    • -cone snails have radula that act as poison darts to subdue prey
    • -lungs in mantle cavity
  30. Bivalvia
    • -clams, oysters, scallops. mussels
    • -halved shell that's hinged together
    • -no head, no radula; some have eyes
    • -mantle cavity contains gills
    • -suspension feeders
    • -water flows through incurrent siphon, gills, excurrent siphon
  31. Cephalopodia
    • -squids, octopuses
    • -predators, have poison and beak-like jaws
    • -foot has been modified into a muscular excurrent siphon and part of the tentacles
    • -no hard shell- or internal; only one with external is chambered nautiluses
    • -only molluscs with closed circulatory systems; complex brain
    • -ammonites = shelled mollusks (octopuses and squids had them but lost them in evolution due to predatory lifestyles)
    • -squids:
    • -giant squid Architeuthis dux has a mantle thats up to 2.5 m long
    • -large suckers and small teeth on tentacles
    • -M. hamiltoni had a mantle of 2.5 m, some think they are even larger
    • -two rows of sharp hooks on tentacles
    • -both live in deep sea; sperm whale is their only predator
  32. extinction of mollusks
    • -molluscs have largest extinctions
    • -freshwater bivalves and land gastropods are most threatened
    • -pearl mussel, pacific island snails
    • -reasons: pollution, habitat loss, and competition
  33. Annelids
    -segmented worms, coelomates
  34. -Polychaetes
    • -has a pair of paddle-like structure called parapodia that functions in locomotion
    • -each parapodium has numerous chaetae = bristles made of chitin
    • -supplied with blood vessels and also functions as gills
    • -fan worms- tube-dweller builds tubes by mixing mucus with bits of sand and broken shells
  35. -Oligochaetes
    • -sparse chaetae
    • -earthworms eat through the soil for nutrients
    • -"tube within a tube" = inner tube is digestive tract, outer tube is forming the body wall (have circulatory system and nervous system within)
    • -till and aerate the soil (good for farmers)
    • -hermaphrodites - mate by aligning next to each other and exchange sperm
    • -sperm gets stored in clitellum = a cocoon of mucus, which slips of the worms head
    • -some reproduce asexually
  36. -Anatomy of an earthworm
    • -coelom is partitioned by septa
    • -metanephridium = excretory tubes with ciliated funnel shaped openings called mephrostomes
    • -abundant blood vessels in the earthworm's skin, functioning as a respiratory organ
    • -nerve cords penetrate the septa and run the body
    • -closed circulatory system
    • -cerebral ganglia = brain, nervous system
    • -chaetae 4 pairs in each segment used for burrowing
    • -surrounded by longitudinal muscle which is surrounded by circulatory muscle - move by contracting these two muscles
  37. -Leeches
    • (freshwater and some marine and terrestrial)
    • -some are parasites that suck blood, secreting an anesthetic
    • -use a chemical called hirudin to which keeps the blood from clotting
  38. Ecdosyozoans
    • -shed a tough external coating called cuticle
    • -this process is known as molting
  39. Nematoda
    • -no segmented bodies, fine tip at posterior end, blunt at anterior end
    • -have an alimentary canal but no circulatory system
    • -they molt their cuticle periodically
    • -have sexual reproduction with internal fertilization (zygote is resistant)
    • -play an important role in decomposing and nutrient recycling
    • -C. elegans is well studied in biology
    • -parasitize plants and infect roots of crops
    • -T. spirals causes trichinosis in humans through eating undercooked pork (they travel through lymphatic system and skeletal muscles)
    • -they can redirect some of the cellular functions of their hosts and evade immune system
    • -Trichinella parasitize animals
    • -controls the expression of specific muscle cell genes that code for proteins that make the cell elastic enough to house the nematode. they also release signals that promote the growth of new blood vessels which supply the nematode
  40. Arthropods
    • -most are insects
    • -successful body plans: segmented body, hard exoskeleton, and jointed appendages
    • -lobopods are an extinct group from which Hallucinogenia came from (also trilobites)
    • -as they evolved, their segmented bodies fused and became fewer resulting in efficiency
    • -2 unusual Hox genes which influence segmentation
    • -body plan did not arise from acquisition of new Hox gene, but by changes in the sequence or regulation of existing Hox genes
  41. Arthropods characteristics:
    • -jointed and paired appendages for feeding, sensory, walking, reproduction and defense
    • -thick cuticle which is exoskeleton used for protection and points of attachment for muscles and joints
    • -shell requires molting
    • -help prevents desiccation, anchors the body
    • -sensory organs: eyes, olfactory (smell) receptors, antennae for touch and smell
    • -concentrated at the anterior end (exception: female butterfly smells with feet)
    • -have open circulatory system = with fluid called hemolymph and is propelled through heart and arteries (arose independently from molluscs)
    • -closed circulatory system has blood
    • -hemolymph-filled body sinuses = hemocoel (not part of the coelom)
    • -gas exchange: gills for aquatic, internal surfaces for terrestrial, insects have tracheal systems (branched air ducts that lead into the interior)
  42. -Chelicerates (scorpions, ticks, mites, spiders, horseshoe crab,sea spiders)
    • -claw-like feeding appendages -> pincers or fangs
    • -anterior cephalothoranx, posterior abdomen
    • -have simple eyes, lack antennae
  43. eurypterids
    water scorpions = earliest one
  44. arachnids
    • scorpions, spiders, parasitic bloodsucking ticks, parasitic mites
    • -6 pairs of appendages:
    • -chelicerae
    • -pedipalps = used for feeding, sensing, or reproduction
    • -4 walking legs
    • -spiders have gas exchange through book lungs = stacked platelike structures contained in an internal chambers, has increased surface area
    • -spiders catch insects by constructing perfect silk webs (used for rapid escape,cover for eggs, even gift wrap for food in courtship, ballooning for transportation)
  45. Myriapods (millipedes and centipedes)
    • -terrestrial only
    • -have antennae and 3 pairs of appendages as mouthparts, including jaw-like mandibles
    • -trunk segment has two fused segments and two pairs of legs (sometimes have thousand legs)
    • -eat decaying leaves and plants (millipedes)
    • -centipedes are carnivores
    • -one trunk region has one pair of legs, poison claws in foremost legs
  46. Hexapods (insects)
    • -very species-rich
    • -anatomy:
    • -head thorax, abdomen
    • -heart = open circulatory system
    • -cerebral ganglion = brain with two nerve cords
    • -tracheal tubes = gas exchange, spiracles are pores that open up to outside body
    • -malpighian tubules = metabolic waste is release by these organs and into digestive tract
    • -gymnosperms influenced early adaptive radiations, then flowering plants did
    • -flight = key advantage; wings come out of thorax; extension of cuticle not appendage
    • -wings first started as absorbing heat and evolved into flight
    • -allowed for gliding from vegetation to ground; and gills in aquatic; functioned for swimming before flight
    • -dragonflies first evolved wings
  47. incomplete metamorphosis
    -nymph (young grasshopper) undergo a series of molts --> final molt they get wings, full size, and sexually mature
  48. complete metamorphosis
    • -larval stage for eating and growing (caterpillar, maggot) --> pupa --> adult
    • -sexual reproduction
    • -use bright colors, sounds, and odors to attract mate; internal fertilization
  49. spermatheca
    • -female has internal spermatheca to store sperm
    • -many mate only once
  50. archaeognatha (bristletails)
    - wingless, live in dark moist habitats
  51. thysanura (silverfish)
    -small, wingless, flattened body, pests)
  52. complete metamorphosis:
    • -coleoptera (beetles) = armored exoskeleton, 2 pairs of wings
    • -diptera (flies and mosquitoes) = 1 pair of wings, mouths suck, pierce or lap, well-developed eyes
    • -hymenoptera (ants, bees, wasps) = highly social, 2 pairs of wings, sucking mouthparts, posterior stinging organ, elaborate nests
    • -lepidoptera (butterflies) = 2 pairs of wings w/tiny scales, uncoil proboscis, feed on nectar
  53. incomplete metamorphosis:
    • -hemiptera (true bugs) = 2 pairs of wings, sucking mouth
    • -orthoptera (grasshopper, crickets) = herbivores, make sounds with hind legs to attract females, legs adapt for jumping
  54. Crustaceans
    • -lobsters, crayfish, crabs
    • -2 pairs of antennae are anterior most appendages
    • -3 or more pairs of mouthpart appendages, including mandible
    • -legs attached to thorax
    • -regenerate lost appendages in next molt
    • -lobsters have internal fertilization while most have swimming larvae
    • -gills for gas exchange and it passes through the cuticle
  55. isopods
    oil bugs, wood lice
  56. decapods
    • lobsters, crayfish, crabs, shrimp
    • -hardened cuticle by calcium carbonate
    • -carapace = portion that covers dorsal side of cephalothorax as a shield
  57. copepods
    • shrimp like krill, feed on algae
    • -barnacles- strong adhesive, strain food from water
  58. Echinoderms
    • -sea stars, sea urchins
    • -closely related to chordates
    • -radial cleavage and anus formation from blastopore
    • -slow moving, sessile animals
    • -unique: water vascular system = a network of hydraulic canals branching into extensions called tube feet that function in locomotion and feeding
    • -sexual repro includes reelasing gametes into the water
    • -not truly radial
  59. Asteroidea (sea stars and sea daisies)
    • -chemical adhesive from tube feet
    • -turns stomach inside out to eat; allows sea stars to consume large mollusks
    • -can regenerate
    • -sea daisies are disk shaped and absorb nutrients outside of the body
  60. Anatomy of a sea star:
    • -water vascular system goes through central disk and radial canal-digestive glands secrete digestive juices (in arms)
    • -central disk = nerve ring and nerve cords radiating from the ring
    • -spines cover the outer layer
    • -madreporite = water flows in and out of these openings
  61. ophiuroidea (brittle stars)
    -distinct central disk and long, flexible arms
  62. echinoidea (sea urchins and sand dollars)
    • -no arms, but have 5 rows of tube feet
    • -pivot their long spine
    • -spherical
  63. crinoidea (sea lilies and feather stars)
    • -live by a stalk
    • -feather starts crawl by using their long arms
  64. holothuroidea (sea cucumbers)
    • -lack spines, look like a cucumber
    • -have 5 rows of feet