Test #1 Material

What is an animal?

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Mutlicellular, heterotrophic (get their own food), eukaryotes Cells do not have cell walls Have nervous and muscle tissues Usually reproduce sexually These are characteristics of MOST animals.

Reproduction

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Sperm + Egg => Zygote (fertilized egg) => 8 cell ball (cleavage)=> Blastula (hollow ball of cells) => Gastrula

Evolution of Animals

 Most scientists agree that the animal kingdom is:  Monophyletic- came from a common ancestor  Has branches where each adaptation comes in

Parazoa “beside the animals”

 Has no true tissues  Sponges

Eumetazoa

  2 branches based on symmetry Radial     ex.) jellyfish and relatives has a top and a bottom no head or rear no left or right   Bilateral    Ex.) all other animals Has a top and bottom Has a head and a tail Has left and right sides

Acoelomates

 Evolution of body cavities  More complex animals  Started without body cavities  Ex. Flatworm

Acoelomates Continued

 Then the insides were suspended in a fluid filled region and could move around without disturbing each other.

 Ex. Roundworms

Protostomes and Deuterostomes

 During the gastrula phase the hollow ball developed a tube in the middle.

 In protostomes, the first opening becomes the mouth (clams, snails, squids, worms, crustaceans, insects, and spiders)

Protostomes and Deuterostomes Continued

 In deuterostomes, the first opening becomes the anus (sea stars, sea urchins, and vertebrates)

How Classification Began

 Classification – grouping of objects or information based on similarities  Taxonomy – branch of biology for grouping and naming organisms  Taxonomists – a biologists who studies taxonomy  Aristotle  Developed the first method of classification  Grouped them into 2 groups: plants and animals  His system was useful but did not group organisms according to their evolutionary history

Classification Continued

 Linnaeus  Developed method we still use today   Based on structural and physical similarities of organisms Binomial nomenclature - gives each organism 2 names.

   The proper way to write a scientific name  Example: animalia, vertebrata, mammalia, primata, hominidae, Homo sapien All letters are lower case except the genus is capitalized. Genus and species are underlined

Animal classification

 Kingdom  Phylum  Class  Order  Family  Genus  Species Largest Smallest  These groups are called taxa.

 Kings play chess on flat green stools.

Scientific Names

 Scientific Names are written in Latin because:  the language is no longer used  the words stay the same and cannot change since the language is dead  the words only have one meaning  Common names are misleading because any organism can have multiple common names

Dichotomous Key

 A set of paired statements used to help identify organisms  Read each statement and decide which fits your organism  Go to where that statement tells you and read the next two statements  Eventually you will reach a statement that tells you the name of the organism

Phylogenetic Classification Models

    Species that share a common ancestor also share an evolutionary history Phylogeny – the evolutionary history of a species  Phylogenetic classification reveals the evolutionary relationships of species Cladistics   System of classification that is based on phylogeny As groups of organisms diverge and evolve from a common ancestral group, they retain some unique inherited traits.

Cladogram    Branching diagram identifying a group’s derived traits. Similar to a pedigree or family tree.

Two groups on diverging branches probably share a more recent ancestor than those groups farther away.

Invertebrates

Phylum: Porifera (sponges)

    Classes: 4 Orders: 18 Families: 80 Species: about 10,000  No tissues because cells are not specialized  No nerves or muscles, but cells can sense and react to changes in the environment  Of 10,000 species, 100 of those are in freshwater

Porifera

     Sack of cells with pores Top opening is called the osculum-where water exits out of the sponge Water goes in through the pores called the spongocoel Under certain conditions, the cells contract and close all of the openings Filter feeders

Porifera Reproduction

 Asexual Reproduction:  Budding   Can regenerate lost parts Can reproduce asexually from a broken piece of the parent  Sexual Reproduction  Hermaphrodites (have both male and female parts)   Produces both sperm and egg Sperm shoots out into the water and is then taken back in (some sponges that are around cross are fertilized)

Phylum:Cnidaria(hydras, jellies, sea anemonies, and coral)

    Classes:4 Orders:27 Families: 236 Species: 8,000-9,000  Have a single opening that is both the mouth and anus  Sack with one digestive compartment

2 Forms of Cnidarians

   Polyp (hydras and sea anemones)  Tentacles push food into the mouth Medusa (Jellies) Tentacles have NEMATOCYSTS – stinging cells that grab and immobilize prey using toxins. 

Cnidarian Reproduction

 Asexually – budding (polyp form)  Sexually –have separate male and female medusae that produce gametes that join through external fertilization

Phylum: Platyhelmenthes (Flukes

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and Tapeworms)

Classes: 4 Orders: 35 Families: 360 Species: 17,500  flatworms    Some are microscopic and can grow to be up to 20 m long.

Still only have one opening and one digestive cavity Absorb nutrients across their body surface

Flukes

 Live as parasites in or on other animals  Attach with suckers to internal organs or to the outer surface

Tapeworms

     Also Parasites in or on other animals Head has suckers and hooks that lock into intestines Absorbs food digested by Humans Absorbs nutrients from digested food Eggs leave host in the feces

Transmission

 This is why you shouldn’t drink contaminated water  Some cows have the eggs in their muscles  When we eat under cooked meat, you have a chance of contracting worms  Can be 20m in length and can block intestines

Flatworm Reproduction

 Sexually - Hermaphrodites – internal fertilzation.

 Asexually – fission – when damaged, regenerates new body parts.

Phylum: Nematoda( pinworms &

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hook worms)

Classes: 4 Orders: 25 Families: 185 Species: 20,000    Humans host about 50 species Also attacks animals and plant roots One species is called Trichinella spiralis  causes trichinosis   Caused by eating undercooked infected pork or other infected meat They can go into human muscles or other organs.

Roundworm Feeding

   Have a simple digestive system.

Have a mouth and an anus Parasitic roundworms use specialized structures (usually with hooks) to attach to a host.

An Important Group

 Many nasty parasitic infections in humans, livestock

Hookworm

Hookworm

Phylum: Nemertea

      1,200 species Probiscis worms or ribbon worms Can be marine, freshwater, or live in damp soil Size ranges from .5cm to over 50m Sexual and asexual reproduction Have a complete digestive tract & a closed circulatory system.   Blood is enclosed in vessels Have no heart, but blood is propelled by muscles squeezing the vessels

Phylum: Annelida

       Classes: 3 Orders: 31 Families: 130 Species: 12,000 Segmented worms (Annelida means “little rings”) From 1mm to 3 m > giant Australian earthworm

Class: Oligochaeta

 Earthworm   Divided by septa Digestive tract, blood vessels, and nerve cords penetrate septa and run the length of the body

Oligochaeta Reproduction

     Hermaphrodites, but they cross fertilize 2 earthworms align and exchange sperm then they separate They store the sperm while an organ produces a mucous cocoon. The cocoon then slides along the worm and picks up the eggs, then the sperm The cocoon slips off the head and stays in the soil until it hatches

Oligochaeta Reproduction

  They can also reproduce asexually by breaking apart They eat their way through the soil and absorb nutrients through the soil

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Class: Hirudinea

Leeches Most live in fresh water, but some can live in moist vegetation Some feed on other invertebrates, but some are blood sucking parasites that feed by attaching to the host.

Most abundant in the tropics.

From 1-30cm long • Hermaprodites but can cross fertilize • Copulation is similar to the earthworm, by making cocoons and buries them in the dirt

Feeding

    Some use blade like jaws to slit the skin of the host while others use an enzyme to digest a hole in the skin Host is usually unaware because the leech secretes an anesthetic Also secretes an enzyme (hirudin) that keeps the host’s blood from coagulating It then usually sucks as much blood as it can   usually 10X it’s weight can usually last a month without another meal

Fig. 26.27, p. 440 Slide 37

Human Benefits

  Was used by doctors for blood letting Still used to treat bruised tissue and to stimulate blood flow to reattached fingers and toes

Phylum: Mollusca

(Snails, slugs, oysters, clams, octopuses, & squids)   1.

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Soft bodies but most are protected by shells All have 3 main body parts  Muscular foot usually used for movement  Visceral mass contains most internal organs  Mantle fold of tissue over a visceral mass that secretes a shell

Class: Gastropoda (snails)

    Most are either male or female but many snails are hermaphrodites.

Have spiral shells that the animal can retreat into Some have tentacles on their head w/ eyes at the tips Move by rippling the foot

Class: Bivalvia (Clams, oysters, mussels, & scallops)

 Divided shells w/ a hinge  Muscle pulls the halves together to protect the body  When open, the foot comes out to move the animal or to dig.

 Water flows in through an incurrent siphon, passes over the gills then exits through an excurrent siphon  They trap food in the mucous that lines the gills  Secrete threads that attach them to rocks, docks boats, etc.

Class: Cephalopoda (Squids, Octopuses)

   Giant squids can be up to 17m long and can weigh 2 tons  Carnivores Shell is reduced and internal in squids and is gone in octopuses Cephalopods have well developed nervous systems and a complex brain and sensory organs.

Cephalopoda Life

    Octopuses live on the sea floor. They creep and scurry searching for crabs and other food.

They inject poison to immobilize the prey Mouth is at the center of the tentacles Squids move by shooting water out of an excurrent siphon (steers by pointing the siphon in different directions)

Phylum:Echinodermata

General Characteristics

Classes: 6 Orders: 36 Families: 145 Species: 6,000 •Live in marine habitat •Radial symmetry •Larval stage has bilateral symmetry •Body wall bears a number of spines, spicules, or plates made of calcium carbonate •No brain •Nervous system allows them to respond to information about feed, predators, etc.

•Tube Feet – fluid filled muscular structures that have suckerlike adhesive disks •Use tube feet for walking, burrowing, clinging to rocks or gripping a meal •Water-Vascular System •Unique to echinoderms •A system of canals delivering water to tube feet •Each tube foot has an ampulla – a fluid filled muscular structure shaped like a rubber bulb •As an ampulla contracts, it forces fluid into the foot and causes it to lengthen

•Reproduction •Sexes separate (few hermaphrodites) •Large gonads •No elaborate copulatory apparatus •Fertilization usually external

Class Asteroidea

•Starfish and sea stars •Most have a flattened, flexible body with rays (often 5) arranged around a central disc •The top side (aboral surface) contains the anus and the entrance to the water vascular system called a madreporite •Sea stars swallow their prey whole •Get rid of coarse undigested residues through the mouth. Anus is too small to get rid of clam shell

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Ambulacral Groove Mouth

1. Arm 2. Gonad 3. Stomach 4. Pyloric cecum

Sand Dollars

• Flattened body in endoskeleton plates • Burrow through sand for food • Filter feed • Mouth on oral surface and anus off to one side