Life On Planet Earth Exam 3

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Animals

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eukaryotic, multicellular, heterotrophic organisms that obtain nutrients byingestion, able to digest their food within their bodies

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“body plan"

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general features of body structureand,– more recently, genetic

two variations: 1. the stationary polyp and2. the floating medusa.

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tissue

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n ensemble of similar cells from the same originthat together carry out a specific function

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Radial symmetry

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refers to animals that areidentical all around a central axis

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Bilateral symmetry

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exists where there is only oneway to split the animal into equal halves

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Invertebrates

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– are animals without backbones, represent 95% of the species in the animalkingdom

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Sponges

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represent multiple phyla

The body of a sponge resembles a sac perforatedwith holes

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Choanocyte

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cells set up currents to draw waterthrough the walls of the sponge and collect small food particles carried by the water current

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Amoebocytes

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are mobile cells that move likeamoebae (via pseudopodia). Similar to some ofthe white blood cells of vertebrates, amoebocytesare found in the sponge wall and play a role in thedefense of the organism against pathogens

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Cnidarians

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are characterized by– the presence of body tissues,– radial symmetry, and– tentacles with stinging cells

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cnidocytes

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(“stinging cells”) for defense and to capture prey

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Molluscs

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represented by soft-bodied animals and usually protected by a hard shell

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radula

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to scrape up food off of a hard substrate.

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The body of a mollusc has three main parts:

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1. a muscular foot used for movement

2. a visceral mass containing most of the internal organs

3. a mantle, a fold of tissue that secretes the shell (if present).

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Gastropods

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include snails, which

– are protected by a single, spiraled shell, or

– have no shell at all, as with slugs and sea slugs.

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Bivalves

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include clams, oysters, mussels, and scallopsand

– have a shell divided into two halves hingedtogether.

– have lost cephalization (they have no head!) but are evolutionarily very successful

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Cephalopods

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– include squids and octopus,

– typically lack an external shell, and

– are built for speed and agility.

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Flatworms (phylum Platyhelminthes)

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are the simplest bilateral animals.

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gastrovascular cavity

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is highly branched and– provides an extensive surface area for absorption of nutrients. a central digestive compartment with only one opening

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Annelids (phylum Annelida

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have bodysegmentation, a subdivision of the body along itslength into a series of repeated parts.

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earthworms

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which eat their way through soil,

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polychaetes

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marine worms with segmental appendages for movement and gas exchange,

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leeches

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typically free-living carnivores but with some bloodsucking forms.

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complete digestive tract

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two openings, a mouth and anus, and– one-way movement of food (increasedefficiency)

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Roundworms (phylum Nematoda)

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cylindrical in shape, tapered at both ends, and– the most numerous and widespread of all animals. important decomposers and– dangerous parasites in plants, humans, and other animals.

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Arthropods (phylum Arthropoda)

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named fort heir jointed appendages. There are over 1 million arthropod species identified, mostly insects.

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exoskeleton

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an external skeleton thatprovides

– protection and

– points of attachment for the muscles that moveappendages.

– limitations on body growth so it must beperiodically shed (which renders the “naked”animal more vulnerable to predation)

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Arachnids

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usually live on land,

– usually have four pairs of walking legs and aspecialized pair of feeding appendages, and

– include spiders, scorpions, ticks, and mites.

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Crustaceans

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are nearly all aquatic,

– have multiple pairs of specialized appendages, and

– include crabs, lobsters, crayfish, shrimp, andbarnacles.

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Millipedes

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eat decaying plant matter and– have two pairs of short legs per body segment

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Centipedes

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are terrestrial carnivores with poison claws and– have one pair of short legs per body segment

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Insects

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typically have a three-part bodyconsisting of

1. head,

2. thorax, and

3. abdomen

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metamorphosis

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Young insects may

– appear to be smaller forms of the adult (nymphs) or

– change from a larval form to something muchdifferent as an adult (the process ofmetamorphosis).

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Echinoderms (phylum Echinodermata)

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lack body segments,

– typically show radial symmetry as adults butbilateral symmetry as larvae (secondary radialsymmetry),

– have an endoskeleton, and

– have a water vascular system that facilitatesmovement and gas exchange

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Vertebrates

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have unique endoskeletonscomposed of

– a cranium (skull) and

– a backbone made of a series of bones calledvertebrae.

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Chordata

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Vertebrates are a subgroup within the phylum

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Chordates (phylum Chordata)

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share four keyfeatures that appear in the embryo and sometimesthe adult:

1. a dorsal, hollow nerve cord,

2. a notochord,

3. pharyngeal slits, and

4. a post-anal tail.

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Chordates consists of three groups ofinvertebrates

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lancelets are blade like animals without a cranium,

2. tunicates, or sea squirts, also lack a cranium, and

3. hagfishes are eel-like forms that have a craniumbut no vertebral column.

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Hagfish (also part of Agnatha

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also lack jaws,– have a cranium, but– have lost their vertebral column.

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The two major groups of living fishes are the

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1.cartilaginous fishes (sharks and rays), with a flexible skeleton made of cartilage, and

2. bony fishes, with a skeleton reinforced by hard calcium salts.

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Bony fishes include

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ray-finned fishes and

– lobe-finned fishes.

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lateral linesystem

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detects minor vibrations in the water

bony fish typically have swim bladders

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Amphibians

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exhibit a mixture of aquatic and terrestrialadaptations,

– usually need water to reproduce, and

– typically undergo metamorphosis from an aquaticlarva to a terrestrial adult.

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amniotes

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are fluid-filled,

– have waterproof shells, and

– enclose the developing embryo.

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ectotherms

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Non-bird reptiles

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Mesozoic Era

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Dinosaurs evolved ~200 mya and were– the most diverse reptile group and– the largest animals ever to live on land

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mammals

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arose ~200 million years ago and– were probably small, nocturnal insect-eaters.

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There are three major groups of mammals:

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monotremes, egg-laying mammals,

2. marsupials, pouched mammals with a placenta,and

3. eutherians, also called placental mammals.

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Eutherian placentas

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provide more intimate andlong-lasting association between the mother andher developing young than do marsupialplacentas

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Humans are primates

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lorises,– pottos,– lemurs,– tarsiers,– monkeys, and– non-human apes.

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Ecology

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scientific study of the interactionsbetween organisms and their environments.

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Biotic factors

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the living component of the environment

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Abiotic factors

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are the environment’s nonliving component

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Habitat

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is the specific environment it lives in

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Ecology can be divided into four increasinglycomprehensive levels:

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1. organismal ecology,2. population ecology,3. community ecology and4. ecosystem ecology

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Organismal ecology

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concerned withevolutionary adaptations that enable individualorganisms to meet the challenges posed by theirabiotic environments

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Population ecology

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addresses populations, groups of individuals ofthe same species living in a particular geographicarea

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Community ecology

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is concerned with communities, all the organismsthat inhabit a particular area

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Ecosystem ecology

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– is concerned with ecosystems, all the abioticfactors in addition to the community of species in acertain area

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biosphere

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the global ecosystem

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Hydrothermal vents

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ecosystems powered by chemoautotrophicbacteria that derive energy from the oxidation ofinorganic chemicals such as hydrogen sulfide

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Osmosis

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The diffusion of water across a semipermeable membrane from an area of lower-solute concentration to an area of higher-solute concentration

isotonic vs. hypotonic vs. hypertonic environments

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Remember

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evolution is goallessand purposeless

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Acclimation

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gradual

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biome

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a major terrestrial or aquatic life zone

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photic zone

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light is availablefor photosynthesis

the shallow water near shore

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aphotic zone

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is deeper and– has light levels too low to support photosynthesis.

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benthic realm

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– at the bottom of all aquatic biomes,

– made up of sand and organic and inorganicsediments, and

– occupied by communities of organisms that arecollectively called benthos.

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phytoplankton

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nitrogen and– phosphorus

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wetland

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an aquatic ecosystem and– a terrestrial one

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pelagic realm

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includes all of the open water ofthe oceans

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zooplankton

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– fishes, and– marine mammals.

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coral reef

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in the photic zone of warm tropical waters,

– in scattered locations around the globe.

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intertidal zone

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the ocean meets land,– the shore is pounded by waves during high tide,

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Estuaries

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are a transition area between a river and theocean,

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Temperate zones

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generally have milder climatesthan the tropics or the polar regions

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Tropical forests

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occur in equatorial areas,

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Savannas

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are dominated by grasses and scattered trees,

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Deserts

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are the driest of all biomes

– may be very hot or very cold

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Chaparral

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has a climate that results from coolocean currents circulating offshore and producing

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Temperate grasslands

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are mostly treeless,– have 25–75 cm (10–30 inches) of rain per year,– experience frequent droughts and fires, and– are characterized by grazers including bison andpronghorn in North America.

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Temperate broadleaf forest

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occurs throughout midlatitudes where thereis sufficient moisture to support the growthof large trees, ranging from 75 to 150 cm(30 to 60 inches)

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Coniferous forests

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are dominated by cone-bearing evergreen treesand– include the northern coniferous forest, or taiga, thelargest terrestrial biome on Earth

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Temperate rain forests

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are found along coastal North America from Alaskato Oregon and– are also coniferous forests.

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Tundra

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covers expansive areas of the Arctic between thetaiga and polar ice

permafrost (permanently frozen subsoil),

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Polar ice

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covers the land

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Sustainability

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the goal of developing,managing, and conserving Earth’s resources inways that meet the needs of people today withoutcompromising the ability of future generations tomeet their needs

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Greenhouse gases

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include CO2, water vapor, and methane,

– are transparent to solar radiation,

– absorb or reflect heat, and

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carbon footprint.

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The amount of greenhouse gas emitted as theresult of the actions of a single individual