Invertebrates Chapter 33. Most animals - invertebrates - do not have backbone.
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Transcript of Invertebrates Chapter 33. Most animals - invertebrates - do not have backbone.
Invertebrates
Chapter 33
• Most animals - invertebrates - do not have backbone.
http://www.edsci-affiliates.com/images/invertebrates_divider.jpg
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.
http://www.gcb.vic.gov.au/gallery/SEA%20SPONGE,%20PORIFERA.jpg
• 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)
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.
• 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.
http://library.thinkquest.org/26153/marine/sketch/613.jpg
• 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.
3Phylum Ctenophora
• Comb jellies named for fused cilia.
• Resemble medusa stage of cnidarians.
• No stinging cells present.
4Phylum Platyhelminthes
• Flatworms, both parasitic and non-parasitic.
• Flatworms have mesoderm - middle layer of tissues - makes them bilateral.
http://www.waterworxbali.com/Images/Photos/Large/pseudoceros-ferrugineus.jpg
• Gastrovascular cavity with only 1 opening; absorb materials across tissue.
• Flatworms are divided into four classes: Turbellaria, Monogenia,Trematoda (flukes), and Cestoidea (tapeworms).
Turbellaria
http://en.wikipedia.org/wiki/Turbellaria
Trematoda
http://en.wikipedia.org/wiki/Trematodes
http://www.saudeanimal.com.br/imagens/platelmintos.jpg
Cestoidea
• 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).
Planaria
• 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.
Blood fluke
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.
http://planktonweb.ifas.ufl.edu/Asplanchna.jpg
• Some rotifers exist only as females that produce more females from unfertilized eggs - parthenogenesis.
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.
http://sps.k12.ar.us/massengale/clip0051.jpg
• 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).
Chiton
http://cache.eb.com/eb/image?id=65301&rendTypeId=4
Gastropod
http://www.marinefoundation.org/mussels_600.jpg
Bivalves
http://home.earthlink.net/~snailstales/cephalopods.jpg
Cephalopod
• 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).
• 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.
• 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.
Nautilus
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.
http://www.inhs.uiuc.edu/~sjtaylor/cave/cave_olig.jpg
• 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.
• Hermaphrodites - exchange sperm which are stored, then later fertilize egg.
• Phylum Annelida divided into 3 classes: Oligochaeta (earthworms), Polychaeta (bristle worms), and Hirudinea (leeches).
http://www.pmel.noaa.gov/vents/nemo/explorer/bio_gallery/biogallery-ImageF.00049.jpeg
Polychaeta
http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb6pg1_files/earthworm1.jpg
• Segmentation of worms allow for specialization.
• Hirudinea - leeches – parasitic, suck blood off hosts.
• Used in medicine because they promote circulation in areas of body.
Hirudinea
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)
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.
• 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.
http://www.geocities.com/SouthBeach/7648/internal.jpg
• Aquatic arthropods - gills for breathing; terrestrial arthropods - internal structures for breathing.
• Insects - tracheal tubes to breathe.
http://www.dwm.ks.edu.tw/bio/activelearner/44/images/ch44c3.jpg
• 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).
Trilobite
Horseshoe crab
• Most spiders - book lungs allow them to breathe.
• Some can inject poison to kill prey.
• 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.
Millipede
• 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.
• Metamorphosis occurs in insects; can be either incomplete (grasshoppers) or complete (butterflies).
• Reproduction in insects usually sexual, with separate male and females.
• Many arthropods live in water. • Crustaceans include lobsters,
crabs, crayfish, shrimp, and barnacles.
• 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).
http://limnology.wisc.edu/personnel/pieter/Hidden%20Stuff/Daphnia/SCDbody.jpg
• 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.
http://farm1.static.flickr.com/1/380353_028542ead3.jpg
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.
http://www.education.umd.edu/blt/pic/Echinoderm.jpg
• 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)
http://www.arctic.noaa.gov/aro/russian-american/photo-gallery/brittle-stars-Photo-B-Bluhm.JPG
• 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.
Sea star
Brittle star
• 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.
Sea urchin
Sea lily
Sea cucumber