Chapter 11Chapter 11Part 1Part 1Animal DiversificationAnimal DiversificationBIOLBIOL 108108Intro to BioIntro to Bio SciSciRobRob SwatskiSwatskiAssoc ProfAssoc Prof BiologyBiologyHACCHACC--YorkYork
11·1–11·3Animals arejust onebranch of theEukaryadomain.
11.1 What is an animal?11.1 What is an animal?Three Key Characteristics
Take-Home Message 11.1Animals are organisms that share threecharacteristics:1) All of them can move during at least onestage of development.2) All of them eat other organisms.3) All of them are multicellular.
11.2 Four key distinctions11.2 Four key distinctionsdivide the animals.divide the animals.
1) Does the animal have1) Does the animal have defineddefinedtissuestissues, with specialized cells?, with specialized cells?
2) Does the animal develop with2) Does the animal develop withradial symmetry or bilateralradial symmetry or bilateralsymmetry?symmetry?A body structured like a pieorA body with a left and right side, whichare mirror images
3) During development, does3) During development, doesthe animal’s gut develop fromthe animal’s gut develop fromfront to back or back to front?front to back or back to front?ProtostomesandDeuterostomes
4) Does growth occur by4) Does growth occur bymolting or by addingmolting or by addingcontinuously to the skeletalcontinuously to the skeletalelements?elements?
Take-Home Message 11.2 The animals probably originated from anancestral protist. Four key distinctions divide the extantanimals:1) Tissue or not2) Radial or bilateral symmetry3) Protostome or deuterostome development4) Growth through molting or through continuousskeletal enlargement
11.3 Everything that is not11.3 Everything that is notextinct is evolutionarilyextinct is evolutionarilysuccessful.successful.
What is “success” evolutionarily?What is “success” evolutionarily?Extant or Extinct
Take-Home Message 11.3 From an evolutionary perspective, all extantspecies are successful. However, some groups are represented bymore species than others. Among the 36 animal phyla, 9 phyla accountfor more than 99 percent of all describedanimal species.
11.411.4 Invertebrates are the largestInvertebrates are the largestand most diverse group of animals.and most diverse group of animals.
Take-Home Message 11.4 Invertebrates, defined as animals without abackbone, are the largest and most diversegroup of animals, comprising 96% of all theliving species of animals. The invertebrates are not a monophyleticgroup, however, and include protostomes anddeuterostomes.
11.5 Sponges are animals that11.5 Sponges are animals thatlack tissues and organs.lack tissues and organs.
Sponge ReproductionSponge Reproduction How do they do it? Hermaphrodites• Male and female sexual reproductive organs• Free-swimming larvae become sessile adults Asexual reproduction• Budding
Take-Home Message 11.5 Sponges are among the simplest of the animallineages. A sponge consists of a hollow tube with poresin its wall, it has no tissues or organs, and onlythree kinds of cells.
11.6 Jellyfish and other cnidarians11.6 Jellyfish and other cnidariansare among the most poisonousare among the most poisonousanimals in the world.animals in the world.
CnidariansCnidarians Two types of cnidarian bodies:• A sessile polyp• A free-floating medusa Reproduce both sexually and asexually Carnivores that use cnidocysts• Stinging cells
3 Major Groups of Cnidarians3 Major Groups of Cnidarians Corals Sea anemones Jellyfishes
The CoralsThe Corals Small, soft-bodied polyps living in largecolonial groups Secrete calcium carbonate Stinging tentacles surrounding a mouth Sexual and asexual reproduction
How is global warming affecting theHow is global warming affecting thecoral reefs of the world?coral reefs of the world?
The Sea AnemonesThe Sea Anemones Resemble flowers Free-swimming larval stage Adult stage settles• But may crawl slowly
The JellyfishesThe Jellyfishes Range tremendously in size Some species deadly
Take-Home Message 11.6 Corals, sea anemones, and jellyfishes areradially symmetrical animals with definedtissues, in the phylum Cnidaria. All cnidarians are carnivores and usespecialized stinging cells located in theirtentacles to capture prey.
11.7 Flatworms, roundworms, and11.7 Flatworms, roundworms, andsegmented worms come in allsegmented worms come in allshapes and sizes.shapes and sizes.
Annelids:Annelids: PolychaetesPolychaetes Marine worms “Many bristles” Some are burrowing. Some are tube dwelling.
Annelids: EarthwormsAnnelids: Earthworms “Few bristles” Bulk feeders• Consume particles of soil and organic material Castings are valued by gardeners.
Annelids: LeechesAnnelids: Leeches The saliva of blood-sucking leeches containsan anticoagulant substance that preventsblood from clotting. Not all leeches are blood suckers.• More than half the species of leeches arepredators.
Take-Home Message 11.7 Worms are found in several different phylaand are not a monophyletic group. All are bilaterally symmetrical protostomeswith defined tissues. The flatworms and segmented worms(annelids) do not molt; the roundworms do.
Take-Home Message 11.7 Flatworms include parasitic flukes andtapeworms, many of which infect humans. Many roundworms are parasites of plants oranimals and are responsible for severalwidespread human diseases. Earthworms are annelids that play animportant role in recycling dead plantmaterial.
11.8 Most mollusks live in shells.11.8 Most mollusks live in shells.
GastropodsGastropods Snails and slugs are called gastropod mollusks. “Belly foot” Found in both aquatic and terrestrialenvironments, snails and slugs account forthree-quarters of all mollusks.
Bivalve Mollusks Clams, scallops, oysters, and mussels have apair of shells that clamp together. Roughly 8,000 species of bivalves—most ofthem live in the ocean. All are filter feeders.
Take-Home Message 11.8 Mollusks are protostome invertebrates that donot molt. They are the second most diverse phylum ofanimals and include snails and slugs, clamsand oysters, and squids and octopuses.
Take-Home Message 11.8 Most mollusks have a shell for protection, amantle of tissue that wraps around their body,and a specialized tongue called a radula.
11.1011.10 An external skeleton andAn external skeleton andmetamorphosis produced themetamorphosis produced thegreatest adaptive radiation ever.greatest adaptive radiation ever.
Mammals get bigger andMammals get bigger andbigger the more they eat.bigger the more they eat.Why don’t insects?
Take-Home Message 11.10 The arthropods are protostome invertebrates,and with nearly one million species (andprobably at least as many more yet to beidentified), they outnumber all other forms oflife in species diversity.
Take-Home Message 11.10 The ability to fly and the development of abody with a rugged exoskeleton havecontributed to the enormous ecologicaldiversity of insects. The life cycle of most insects includes a larvalstage that is devoted to feeding and growth, apupal stage during which metamorphosisoccurs, and an adult stage in which the insectreproduces.
11.11 Other arthropods include11.11 Other arthropods includearachnids, crustaceans, millipedes,arachnids, crustaceans, millipedes,and centipedes.and centipedes.
Millipedes and CentipedesMillipedes and Centipedes• “A thousand feet” and “a hundred feet”• Long, segmented bodies• Millipedes feed on decaying plant material.• Centipedes are predators; they use venomousfangs to kill insects and even small mammals.
ArachnidsArachnids Land-dwelling arthropods Include spiders, scorpions, mites, and ticks Usually have four pairs of walking legs• And a specialized feeding apparatus Only have legs on the thorax
Spider VenomSpider Venom Arachnids are predators Black widow spider Brown recluse spider
The CrustaceansThe Crustaceans• Lobsters, crayfish, crabs, and shrimps• All have five pairs of appendages extending fromtheir heads.• Many pairs of legs modified for many purposes• Most are aquatic.
Take-Home Message 11.11 Centipedes are predators with fangs thatinject venom, and millipedes are herbivoresthat feed on dead plant material. Spiders and scorpions are predatoryarthropods that eat insects and, occasionally,small vertebrates. Lobsters, crabs, shrimp, and barnacles arepredatory marine crustaceans.
11.12 Echinoderms are11.12 Echinoderms arevertebrates closest invertebratevertebrates closest invertebraterelativesrelativesAnd include sea stars, sea urchins, and sanddollars
Evolutionary SpecializationEvolutionary Specialization Radial symmetry in adults An evolutionary specialization associated withtheir locomotor mode and feedingspecializations
Echinoderms and ChordatesEchinoderms and Chordates Bilateral symmetry in larvae The larvae have anatomical characteristics incommon with the larvae of primitivechordates. Echinoderms and chordates are each other’sclosest relatives.
Take-Home Message 11.12 Because they are deuterostomes (as arevertebrates), echinoderms are theinvertebrates that are the closest evolutionaryrelatives to the vertebrates (and otherchordates). Their aquatic larvae are bilaterallysymmetrical and share some anatomicalfeatures with chordates, but adultechinoderms are radially symmetrical.