Introduction to Animals
Chapter 26
General Features of Animals
• Animals are multicellular, heterotrophic
organisms with cells that lack cell walls.
• Multicellular (made of more than one cell)
• Heterotrophs- organism that obtains food
by eating other organisms.
– Filter feeders = catch particles of food that drift
by in the water.
Movement
• Animals are unique among living things
because animals can move rapidly and in
complex ways.
• Swim, walk, run, and fly.
• Locomotion is a big advantage for animals:
– Finding food
– Avoiding predators
Kinds of Animals
• Kingdom Animalia contains about 35 major
divisions called phyla.
• Animals are often informally grouped as
invertebrates or vertebrates, although
vertebrates make up only a subgroup of one
phylum (Chordata).
• The vast majority of animals are
invertebrates.
Invertebrates
• Include any animal that does not have a
backbone.
• Most primitive = sponges
• Advanced = ants, octopuses.
• Can form the basis of an entire ecosystem.
Vertebrates
• Chordates that have a backbone.
• Many of the animals you see in a zoo:
– Lions, elephants, turtles, snakes, and birds.
• Have a cranium and an internal skeleton
• Backbone supports and protects a dorsal
nerve cord.
• Also provides a site for muscle attachment.
Assignment
• Pg. 626, 1-4
• Read section 2
• Pg. 630, 1-6
Animal Body Systems
• Allows animals to function
• Not all animals have every body system
• Body systems reflect/shape the lifestyles
that animals have
Support
• An animals skeleton provides a framework that
supports the animal’s body.
• The skeleton is also vital to an animals movement.
• Hydrostatic skeleton – a cavity that is
filled with water and that has a support
function
• Endoskeleton – an internal skeleton made
of bone and cartilage
• Exoskeleton – a hard, external, supporting
structure that develops from the ectoderm
Digestive and Excretory Systems
• The digestive system is responsible for
extracting energy and nutrients from an
animal’s food.
• The excretory system removes waste
products from the animal’s body.
Digestive System
• Gastrovascular cavity – a digestive cavity
that serves both digestive and circulatory
purposes in some animals.
• Single-celled organisms do not have a
digestive system.
• Other animals have a digestive tract with
two openings.
Excretory System
• Waste products such as ammonia will hurt
or kill an organism if they are not removed.
• Terrestrial animals need to minimize water
loss.
• Simple aquatic invertebrates and some
fishes excrete ammonia through their skin
or gills.
Nervous System
• The nervous system carries information
about the environment through the body and
coordinates responses and behaviors.
1. Simple Nervous System
2. Complex Nervous System
Respiratory and Circulatory
Systems
• The respiratory system is responsible for
exchanging oxygen and carbon dioxide
between the body and the environment.
• The circulatory system transports gases,
nutrients and other substances within the
body.
Reproduction
• The two types of reproduction in animals is
asexual and sexual.
– Asexual occurs when an individual produces
exact copies of itself and does not mix its genes
with those of others.
– Sexual occurs with a new individual is formed
by the union of a male and female gamete.