Transcript Zoology

Test #1 Material
What is an animal?
1.
2.
3.
4.
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
1.
2.
3.
4.
5.
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
Largest
 Phylum
 Class
 Order
 Family
 Genus
 Species
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
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 &
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
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


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
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.
Soft bodies but most are
protected by shells
All have 3 main body parts
Muscular foot

2.
Visceral mass

3.
usually used for movement
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)
 Carnivores
 Shell is reduced and internal
in squids and is gone in
octopuses
 Giant squids can be up to 17m
long and can weigh 2 tons
 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
Ambulacral
Groove
2. Mouth
1.
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