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Biology 11: Overview of Animals
Overview of Animals (p 730…)
•less than 5% of animal phyla have backbones- called
__ vertebrates eg.__ fish, amphibians, reptiles etc
•more than 95% do not-called_invertebrates eg.
earthworms, insects, snails, etc.
•more than one million animal species identified probably millions more not identified
A. Characteristics of Animals
All Animals...
1. eukaryotic cells
2. multicellular (specializedcells)
3. cells do not have cell walls (therefore felxible)
4. heterotrophic
5. motile (or at least a motile stage in life cycle)
As well, MOST animals...
•have specialized tissues and organs
•are heterotrophic by ingestion
•have two unique types of tissues responsible for
impulse conduction & movement:nervous tissue &
muscle tissue
•similar early embryonic development
How have various animals adapted to a motile
lifestyle?legs, flippers, wings, tails,
tentacles=appendages
What characeristics do animals share with other
organisms?eukaryotic cells, heterotrophci,
multicellular, motility, sex.repr. spec. tissues and
organs
What characteristic(s) distinguishes animals from
other organisms?asexual repro not common,all
motile/motile stage, nerve and muscle tissue, unique
embryonicdevelopment
Why would body cells with rigid cell walls be a
disadvantage to animals?interfere with movement (not
flexible)
B. Essential Functions of Animals (ch 27 and 28)
1. Support and movement (p814-817) (firm enough to
support;flexible enough to move)
Biology 11: Overview of Animals
 Some animals are sessile which means they live
their entire adult lives attached to one spot, but many
animals are motile, which means that they move
around.
•To move, most animals use tissues called musclesthat
generate force by contraction.
•In the most successful groups of animals, muscles
work together with a skeleton, or the system of solid
support in the body. There are 3 types of skeletal
systems:
a) exoskeleton - hard encasement on surface of
animal, eg. insects, crabs, snails, clams, etc. ---> limits
growth & flexibility
b) endoskeleton - rigid framework inside animal
---> doesn’t protect as well as an exoskeleton, but
allows for freer movement, eg. birds, reptiles,
mammals, etc.
c) hydrostatic - some animals do not have a system
of solid support, but instead muscles surround and are
supported by a water-filled cavity, eg. earthworm
2. Feeding and Digestion (p. 782-785)
•to supply energy (for movement, etc.) & nutrients for
growth, repair, etc., animals must find, break down &
absorb food to do this
•animals have different modes of feeding (ways of
obtaining food)
Biology 11: Overview of Animals
Complete the following chart, which compares different modes of feeding.
Mode of Feeding
Description
Examples
Filter Feeder
Strain food (algae and
small animals from
H2O…use modified gills
or other structures)
Feed on tiny bits of
decaying plants and
animals, bacteria, algae,
etc.
Feed on plants, plant parts
eg. Roots, stems, flowers,
fruit, leaves, sap
Eat animals, parts of
animals
Sessile worms,
sponges, barnacles,
some sharks and
whales
Earthworms, marine
worms, crustaceans,
(carbs and lobsters
etc.)
Some birds, and
mammals, insects
Detritus Feeder
Herbivores
Carnivores
Omnivores
Eat both plants and
animals
Parasitic Symbionts
Live on or in another,
feed on tissue/blood/other
fluids
Mutualistic Symbionts
Both organisms benefit
Mammals, wolves etc.
spiders, cnidarians,
hydra, insects,etc.
Humans, bears
Parasitic roundworms
& flatworms
(tapeworms) fleas,
lice
Corals and algae in
their tissues, termites
and gut protists
•digestion can be intracellular (in simple animals) or
extracellular (in digestive tract)
 Intracellular digestion: digest food inside
specialized cells by diffusion (sponges)
Biology 11: Overview of Animals

Extracellular digestion: food is broken down
outside cells in a digestive system and then asorbed
•digestive cavity can be one-way or two-way
3. Gas Exchange (Respiration) (p. 787)
•Living cells consume oxygen & give off carbon
dioxide in the process of aerobic cellular respiration
•Entire animals must respire, or breathe, in order to
take in & give off these gases
•Diffusion of gases between the environment &
animals requires a thin moist membrane
•Small animals that live in wtaer or in moist soil may
respire through their skin
•Large animals - respiration through skin not efficient
enough - respiratory systems have taken many different
forms in adapting to different habitats
4. Sensing the Environment (Nervous System) (p. 808)
•Animals must keep watch on their surroundings to
find food, spot predators, & identify others of their own
kind (for mating, etc.).
•To do this, they use nerve cells, which hook up
together to form a nervous system
•the simplest nervous systems are called nerve nets
•Sense organs, such as eyes & ears, gather information
from the environment by responding to light, sound,
temperature & other stimuli
Biology 11: Overview of Animals
control centre - processes information & regulates how
the animal responds
•complexity of nervous system varies greatly in
animals
5. Internal Transport (Circulatory System)(p. 791-792)
•Some aquatic animals, such as small worms, can
function without an internal transport system
•in small animals, simple diffusion between their body
& the environment is sufficient
•Larger animals must carry oxygen, nutrients & waste
products to & from cells deep within its body
•Many have evolved circulatory systems in which a
pumping organ called a heart forces a fluid called
blood through a series of blood vessels
•circulatory systems can be open or closed:
open circulatory system: blood is NOT always
confined to blood vessels (there are blood
cavities/sinuses)
closed circulatory system: blood is always
confined to blood vessels
6. Excretion (p. 794)
•Cellular metabolism produces chemical wastes such as
ammoniathat are harmful & must be eliminated
•ammonia (NH3) is produced by the breakdown of
amino acids in proteins
•toxic nitrogen-containing compounds are called
nitrogenous wastes
•Small aquatic animals depend on diffusion to carry
wastes from their tissues into the surrounding water,
which then carries wastes away
•Larger animals (in water & on land) must work to
remove poisonous metabolic wastes
NOTE: EXCRETION IS NOT THE SAME AS
ELIMINATION OF UNDIGESTED WASTE (FECES)
•Brain - nervous system’s
Biology 11: Overview of Animals
7. Reproduction (p. 819)
•Animals must reproduce or their species will not
survive.
•Some (like jellyfish) switch back & forth between sexual
and asexual reproduction
•All animals reproduce sexually(some asexually also)
•Sexual reproduction - can bear live young or lay eggs
•Direct development: eggs of some species hatch into
baby animals that look like miniature adults ---> babies
increase in size, don’t change in overall form
•Indirect development: eggs hatch into immature
stages that look & act nothing like the parents (called
larvae) ---> larvae undergo process called
metamorphosis in which they change shape
dramatically as they grow
C. Characteristics Important in Classifying Animals
(p 737…)
1. Symmetry
•refers to the way the animal’s organs & other
structures are arranged
•must make animal an efficient organism that can
compete in its environment
a) asymmetric (no symmetry)
b) radial symmetry - has ventral &dorsal surfaces
(does not have front, back, right or left side)
•tend to be slow moving or sessile
•sense organs located in radial pattern around body
(Why is such an arrangement of sense organs an advantage
to slow-moving or sessile organisms?
Biology 11: Overview of Animals
axis
•generally more complex organs (concentrated at
head end -enables efficient movement
(Why?)
•several terms are used to describe the body of an
organism that has bilateral symmetry
•anterior: head end
•posterior: tail end
•ventral: belly or underside
•dorsal: back or upperside
•medial: middle
•lateral: to the side
2. Segmentation (p 739)
•some or all of body divided into repeating units or
segments
•may be obvious from outside or not (eg. vertebrae each one represents a segment)
•segments may be fused together into larger functional
units (eg. chest or abdomen)
•segmentation enables specialization of body parts &
more complex bodies over all
c) bilateral symmetry parts arranged in pairs
on either side of a central
Biology 11: Overview of Animals
(but cells are specialized
tissues: cells organized into tissues eg. Epithelial, nervous,
muscle, connective
•organs: tissues organized into organs(eg.heart,
kidney, stomach
•organ systems: organs organized into
systems(egreproductive, nervous, circulatory
•level of organization dependent upon number of germ
cell layers
•patterns of tissue development in embryos very similar
to blastula stage (blastula - hollow ball; gastrula - 2layered cup-shaped embryo)
•during formation of gastrula, cell layers develop that
will give rise to different tissues & organs
•the number of cell layers & the way the embryo
develops from gastrula stage varies with the kind of
animal
•most animals have 3 layers:
•ectoderm---> skin, nerves & sense organs
•mesoderm ---> circulatory system, muscles,
reproductive & excretory system
•_endoderm ---> digestive tract & respiratory
system
3. Level of Organization
•cellular: cells not
organized into tissues
Biology 11: Overview of Animals
of digestive tract”)
•sac plan: mouthused for taking in food, getting rid of
wastes
•tube-within-tube: mouth takes in food, anus gets rid
of wastes
•some animals have NO body plan
5. Coelom (Body cavity between digestive tract & body
wall)
a) Coelomates: have true coelom (a fluid-filled body
cavitycompletely lined
with mesoderm that
contains internal organs)
b) Pseudocoelomates: have false coelom - coelom
only partially lined with mesoderm
c) Acoelomates: have no coelom (only fluid-filled
extracellular spaces)
4.
Body Plan(see “type
D. Questions
1. a. Explain “cephalization. (p740
b. what types of animals have pronounced cephalization?
c. Why do animals with heads usually move in a “head-first” direction?
2. Study the chart on p 741, which illustrates several important evolutionary trends. As animals
become more complex, state the evolutionary trend with respect to:
a. Level of organisation
Biology 11: Overview of Animals
b. body symmetry
c. Germ layers
Biology 11: Overview of Animals