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Question: After fertilization, once cell division starts, what is the organism called?
INTRODUCTION TO ANIMALS
All animals have several characteristics in common:
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Animals are eukaryotic, multicellular organisms.
They have ways of movement to help them get food, reproduce and protect
themselves.
Most animals have specialized cells
CELLS
TISSUES
ORGANS
ORGAN SYSTEMS
Symmetry — a balanced arrangement of an animal’s body structures
Radial Symmetry
— parts are arranged
around a central axis
Bilateral Symmetry
— parts are divided with
mirrored image halves
Asymmetrical
(no symmetry)
— no definite shape
Animals do not live forever, so they must reproduce.
Sexual reproduction — process by which a new organism develops from the joining of
two sex cells — a male sperm cell and a female egg cell.
Fertilization — the joining of an egg cell and a sperm cell
Asexual reproduction — process by which a single organism produces a new organism
identical to itself.
Animals are classified according to how they are related to other animals — body
structure, animal development and animal’s DNA.
Question: How does natural selection favor certain behaviors?
ANIMAL BEHAVIOR
Behavior — the way an organism interacts with other organisms and its environment
Stimulus – anything in the environment that causes a response, or a reaction to the
stimulus
Innate behavior – a behavior that an organism is born with
Reflex – automatic response that happen instantaneously
Instinct – complex pattern of innate behavior that may take weeks to complete (Ex.
Spider webs)
Learned behavior – develops during an animal’s lifetime as a result of experience or
practice
Imprinting – newborn forms attachment to another organism after birth or
hatching.
Conditioning – behavior is modified to get desired response from a stimulus
Insight – animals use past experiences to solve new problems
Behavioral Interactions
Social
 Courtship &
mating
Territorial
 Contain food,
shelter & mates
 Caring for young
 Defending
territory is
instinctual
behavior
 Organized society
 Some species
interactions
Communication
 Courtship
behaviors and
rituals
Cyclic
 Innate behavior
involving
repeating patterns
 Aggression is used
to dominate
 Communicate using  Circadian rhythm
pheromones
 Diurnal or
nocturnal
 Sound is used by
some vertebrates &
insects
 Hibernation
 Submission is used
to more dominant
 Light is used by
some organisms
 Migration
Question: What impact do parasitic roundworms have on other organisms?
SPONGES, CNIDARIANS AND WORMS
Sponges — invertebrate animals that usually have no body symmetry (asymmetrical)
and never have tissue or organs.
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Sessile — stuck in one place
Filter feeders — filter food out of water that flows through body
Pores let water into central cavity
Flagella keep water moving through sponge
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Soft bodies protected by sharp spicules
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Reproduce sexually and asexually.
Cnidarians — invertebrates that use stinging cells to capture food and defend
themselves.
 Have two basic body forms — the vase — shaped polyp and the bowl — shaped
medusa
 Capture or poison their prey using nematocyst, or capsules that contain a coiled,
thread — like tube.
 Reproduce sexually by releasing sperm or eggs or asexually by budding.
Worms — classified into three major phyla:
1. Flatworms (Phylum Platyhelminthes)
 long, flattened bodies with organs and systems
 mostly parasites living off or in host
2. Roundworms (Phylum Nematoda)
 body is a tube within a tube
 digestive tract has both a mouth and anus
3. Segmented worms (Phylum Annelida)
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made up of many segments
closed circulatory system where blood moves within blood vessels
nerve cord and digestive tract with mouth and anus
Question: What connects the two shells of a bivalve?
MOLLUSKS, ARTHROPODS & ECHINODERMS
Mollusks — invertebrates with a soft body often covered by a shell; has thin layer of
tissue called a mantle that covers its internal organs, and an organ called a foot —
depending on mollusk is used for crawling, digging or catching prey.
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Lungs or gills that exchange CO2 from the animal for oxygen in the air or water
Most mollusks have open circulatory system in which blood is not always inside
blood vessels
3 major groups include:
Gastropods — have a single external shell or no shell at all (Ex. Snails and slugs)
Bivalves — have two shells held together by hinges and strong muscles (Ex.
oysters, clams, scallops)
Cephalopods — ocean—dwelling mollusk whose foot is adapted to form tentacles
and are only mollusks to have closed circulatory system (Ex. octopus, squid,
nautilus, cuttlefish)
Arthropods — invertebrates that have an exoskeleton or external skeleton, a segmented
body and jointed attachments called appendages.
Characteristic
Crustaceans
(formerly arachnids)
Chelicerates
# body sections
2 or 3
2
2 or 3
Pairs of legs
5+
4
many or 3
Pairs of antennae
2
0
1
lobster, crayfish
spiders, ticks
centipedes, milli
and insects
Examples
(formerly insects)
Uniramians
Echinoderms — invertebrates with an internal skeleton and a system of fluid—filled
tubes called a water vascular system
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Endoskeleton — internal skeleton made of hardened plates
Water vascular system — fluid-filled tubes to help them move and eat
Diets vary – some are predators, some filter feeders
4 major groups – sea stars, brittle stars, sea urchins, sea cucumbers
Question: What happens when an arthropod molts?
INSECTS
Insects — arthropods with three body sections, six legs, one pair of antennae and usually
one or two pairs of wings
 Body sections include head, thorax and abdomen
Insect’s mouthparts are adapted for a highly specific way of getting food.
Each insect species undergoes either complete metamorphosis or gradual
metamorphosis:
Complete metamorphosis - insect goes through four different stages: egg, larva, pupa
and adult
Incomplete gradual metamorphosis – has no district larval stage – eggs hatch into
nymph, or miniature adults without wings, then molt several times before becoming
adult
Insects play key roles in food chains because of the many different ways that they
obtain food and then become food for other animals.
Two ways insects interact with other living things:
1. Pollen carriers – many insects are pollinators, or carry pollen among plants
2. Disease carriers – some insects spread diseases to both plants and animals,
including humans.
Insects are also used to try to control pests. Biological controls are a natural predator or
disease released into an area to fight a harmful insect ( Ex. ladybugs eat aphids)