Invertebrates

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Invertebrates

• Chapter 33

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• Most animals - invertebrates - do not have
  backbone.

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http//www.edsci-affiliates.com/images/invertebrat
es_divider.jpg
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1Phylum Porifera

• Sponges - lack nerves and muscles sessile
  (non-motile).
• Most marine, live in water.
• Most hermaphrodites - each individual produces
  sperm and eggs.
• Can regenerate lost parts.

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http//www.gcb.vic.gov.au/gallery/SEA20SPONGE,20
PORIFERA.jpg
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• Sponges perforated with holes so water can flow
  through them (suspension-feeding)
• Water drawn through pores into central cavity
  (spongocoel) and flows out through larger opening
  (osculum)

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2Phylum Cnidaria

• 1st organisms to have true tissues.
• Basic body plan - sac with central digestive
  compartment (gastrovascular cavity)
• Jellyfish, corals, sea anemones, and hydras.
• Have nerve nets - very primitive nervous systems
  that move towards stimuli.

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• 2 body plans in cnidarians.
• 1Polyp stage - sessile some live whole life this
  way.
• 2Medusa stage - cnidarian can swim freely.
• Can move through both stages during lifetime.

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http//library.thinkquest.org/26153/marine/sketch/
613.jpg
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• Cnidarians have nematocysts - stinging cells.
• Phylum Cnidaria divided into 3 major classes
  Hydrozoa (hydra), Scyphozoa (true jellyfish), and
  Anthozoa (sea anemones).
• Cnidarians - carnivores - use tentacles to push
  food into gastrovascular cavity.

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3Phylum Ctenophora

• Comb jellies named for fused cilia.
• Resemble medusa stage of cnidarians.
• No stinging cells present.

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4Phylum Platyhelminthes

• Flatworms, both parasitic and non-parasitic.
• Flatworms have mesoderm - middle layer of tissues
  - makes them bilateral.

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http//www.waterworxbali.com/Images/Photos/Large/p
seudoceros-ferrugineus.jpg
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• Gastrovascular cavity with only 1 opening absorb
  materials across tissue.
• Flatworms are divided into four classes
  Turbellaria, Monogenia,Trematoda (flukes), and
  Cestoidea (tapeworms).

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Turbellaria
http//en.wikipedia.org/wiki/Turbellaria
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Trematoda
http//en.wikipedia.org/wiki/Trematodes
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Cestoidea
http//www.saudeanimal.com.br/imagens/platelmintos
.jpg
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• Planaria - scavengers found in ponds.
• No organs specialized for circulation or
  respiration exchange gases across membranes.
• Have eyespots for detecting light and lateral
  flaps for smell.
• Nervous systems more advanced than cnidarians
  reproduce asexually through regeneration (can
  sexually reproduce).

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Planaria
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• Trematodes parasites with suckers to attach to
  victims.
• Blood fluke - parasite of humans.
• Tapeworms have suckers and hooks on head anchor
  worm in digestive tract of host.

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Blood fluke
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5Phylum Rotifera

• Rotifers - complete digestive tract with separate
  mouth and anus.
• Internal organs in pseudocoelom - body cavity not
  completely lined with mesoderm.
• Functions as circulatory system -nutrients
  dissolved in cavity.
• Have hydrostatic skeleton - movement.

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http//planktonweb.ifas.ufl.edu/Asplanchna.jpg
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• Some rotifers exist only as females that produce
  more females from unfertilized eggs -
  parthenogenesis.

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6Phylum Mollusca

• Snails, slugs, clams, squid, and octopus.
• Mollusks soft-bodied animals - most protected by
  hard shell of calcium carbonate.
• All have similar body plan with muscular foot
  (locomotion), visceral mass with most of internal
  organs, and mantle.

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http//sps.k12.ar.us/massengale/clip0051.jpg
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• Use radula to feed - allows them to scrape up
  food.
• Most mollusks have separate sexes.
• 4 common classes - Polyplacophora (chitons),
  Gastropoda (snails and slugs), Bivalvia (clams,
  oysters, and other bivalves), Cephalopoda
  (squids, octopuses, and nautiluses).

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Chiton
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http//cache.eb.com/eb/image?id65301rendTypeId4
Gastropod
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http//www.marinefoundation.org/mussels_600.jpg
Bivalves
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Cephalopod
http//home.earthlink.net/snailstales/cephalopods
.jpg
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• Gastropods have shells that they can retreat into
  (means stomach-foot)
• Lining of mantle acts like lungs - allows them to
  live on land (garden snails and slugs).

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• Bivalves - 2-shelled - clams, oysters, mussels,
  and scallops.
• Most bivalves - suspension feeders, trapping fine
  particles in mucus that coats gills.
• Usually sessile - cannot move during lifetime.

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• Cephalopods have reduced shell and include
  nautilus, squid, and octopus.
• Nautilus - external shell.
• Have well-developed nervous system with complex
  brain and well-developed sense organs.
• Cephalopods have closed circulatory system.

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Nautilus
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6Phylum Annelida

• Annelids - segmented worms.
• Digestive system - pharynx, esophagus, crop,
  gizzard, and intestine.
• Closed circulatory system with 5 chambers act as
  heart to pump blood.

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http//www.inhs.uiuc.edu/sjtaylor/cave/cave_olig.
jpg
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• Each segment - pair of excretory tubes,
  (metanephridia) - remove wastes from blood and
  coelomic fluid exits through pores.
• Brainlike pair of cerebral ganglia lie above and
  in front of pharynx.
• Some earthworms reproduce asexually
  (regeneration), also reproduce sexually.

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• Hermaphrodites - exchange sperm which are stored,
  then later fertilize egg.
• Phylum Annelida divided into 3 classes
  Oligochaeta (earthworms), Polychaeta (bristle
  worms), and Hirudinea (leeches).

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http//www.pmel.noaa.gov/vents/nemo/explorer/bio_g
allery/biogallery-ImageF.00049.jpeg
Polychaeta
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http//kentsimmons.uwinnipeg.ca/16cm05/16labman05/
lb6pg1_files/earthworm1.jpg
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• Segmentation of worms allow for specialization.
• Hirudinea - leeches parasitic, suck blood off
  hosts.
• Used in medicine because they promote circulation
  in areas of body.

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Hirudinea
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7Phylum Nematoda

• Roundworms - found in wet environments.
• Complete digestive tract - use fluid in
  pseudocoelom to transport nutrients (lack
  circulatory system)
• Reproduce sexually, can be parasitic
  (trichinosis)

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8Phylum Arthropoda

• Characterized by body segmentation, a hard
  exoskeleton, jointed appendages.
• Body of arthropod completely covered by cuticle -
  exoskeleton constructed from layers of protein
  and chitin.
• Have to molt in order to grow.

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• Arthropods have well-developed sense organs,
  including eyes for vision, olfactory receptors
  for smell, antennae for touch and smell.
• Arthropods - open circulatory system - fluid
  pumped by heart through short arteries into
  sinuses surrounding tissues and organs.

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http//www.geocities.com/SouthBeach/7648/internal.
jpg
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• Aquatic arthropods - gills for breathing
  terrestrial arthropods - internal structures for
  breathing.
• Insects - tracheal tubes to breathe.

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http//www.dwm.ks.edu.tw/bio/activelearner/44/imag
es/ch44c3.jpg
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• Trilobites - extinct arthropods - no
  specialization.
• Chelicerates mostly extinct 4 species, (i.e.
  horseshoe crab) still alive.
• Modern chelicerates members of class Arachnida
  (scorpions, spiders, ticks, and mites).

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Trilobite
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Horseshoe crab
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• Most spiders - book lungs allow them to breathe.
• Some can inject poison to kill prey.

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• Millipedes - worm-like with 2 pairs of walking
  legs on each segment.
• Centipedes - terrestrial carnivores.
• Insects (class Insecta) outnumber all other forms
  of life combined - 26 orders.

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Millipede
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• Insects - ability to fly.
• Metabolic wastes removed from fluid by Malpighian
  tubules, pockets of digestive tract.
• Respiration done by branched, chitin-lined
  tracheal system - carries O2 from spiracles
  directly to cells.
• Nervous system - pair of ventral nerve cords with
  several segmental ganglia.

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• Metamorphosis occurs in insects can be either
  incomplete (grasshoppers) or complete
  (butterflies).
• Reproduction in insects usually sexual, with
  separate male and females.

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• Many arthropods live in water.
• Crustaceans include lobsters, crabs, crayfish,
  shrimp, and barnacles.

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• Small crustaceans exchange gases across thin
  areas of cuticle larger species have gills.
• Circulatory system open - heart pumps fluid into
  short arteries then into sinuses that bathe
  organs.
• Nitrogenous wastes excreted by diffusion through
  thin areas of cuticle, glands regulate salt
  balance of fluid (hemolymph).

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http//limnology.wisc.edu/personnel/pieter/Hidden
20Stuff/Daphnia/SCDbody.jpg
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• Crustaceans - different sexes.
• 3 groups of crustaceans isopods (pill bugs, or
  wood lice), copepods (small crustaceans) and
  decapods (lobsters, crayfish, crabs, and shrimp).
• Barnacles also crustaceans.

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http//farm1.static.flickr.com/1/380353_028542ead3
.jpg
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Phylum Echinodermata

• Most echinoderms sessile, or slow-moving.
• Most - prickly skin.
• Water vascular system - network of hydraulic
  canals branching into extensions (tube feet) used
  for movement, feeding, gas exchange.

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http//www.education.umd.edu/blt/pic/Echinoderm.jp
g
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• Sexual reproduction in echinoderms - release of
  gametes by separate males and females into
  seawater.
• 6 classes Asteroidea (sea stars), Ophiuroidea
  (brittle stars), Echinoidea (sea urchins, sand
  dollars), Crinoidea (sea lilies, feather stars),
  Holothuroidea (sea cucumbers), Concentricycloidea
  (sea daisies)

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http//www.arctic.noaa.gov/aro/russian-american/ph
oto-gallery/brittle-stars-Photo-B-Bluhm.JPG
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• Sea stars can attach to objects with tube feet.
• Can regenerate lost parts.
• Brittle stars do not have suckers on tube feet -
  have long and flexible arms.

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Sea star
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Brittle star
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• Sea urchins and sand dollars - no arms, have 5
  rows of tube feet used for locomotion.
• Sea lilies attached to objects by stalks, feather
  stars crawl using their long, flexible arms.
• Sea cucumbers lack spines - have tube feet.

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Sea urchin
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Sea lily
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Sea cucumber