32-2: Comparison of
Invertebrates + Vertebrates
Invertebrate characteristics

Symmetry

Radial or bilateral
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Aquatic – radial; Terrestrial – bilateral
Most animals display bilateral for motility + sensory
functioning (i.e. a BRAIN)
Segmentation

A body composed of a series of repeating similar
units

Simple (earthworm) to complex (Arthropods)
Let’s look at these two…
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Symmetry

Segmentation
Invertebrate characteristics

Support of the body

Simple skeletons


Pressure fluid-filled cavity


Ex. Sponges
Ex. Roundworms
Exoskeleton – rigid outer covering

Ex. Lobster + clam
Invertebrate characteristics

Respiratory + Circulatory Systems


Gas exchange – CO2 + O2 in blood
Circulatory system – moves blood or fluid
(hemolymph) through body to transport nutrients or
O2 to cells

Types of circulatory systems:


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Diffusion – Ex. Sponges + Cnidarians
Open – bloodlike fluid pumped from vessels into body
cavity, then pumped back; Ex. Grasshopper
Closed – blood circulates through body in tubular vessels;
Ex. Earthworm
Let’s look at these two…

Respiratory

Circulatory
Invertebrate characteristics

Digestive + Excretory systems

Digestion


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
Sponges –occurs in individual cells
Cnidarians – central chamber
Most others have a digestive tract (gut) to breakdown
food to absorb nutrients
Excretion – removal of wastes


Aquatic – wastes are excreted as dissolved ammonia
(NH3)
Terrestrial – wastes are filtered before removed;
water gets reabsorbed
Let’s look at these two…

Digestive

Excretory
Invertebrate characteristics

Nervous System

Sponges



No neurons – nerve
cells
Individual cells can
react to external
stimuli
Most other organisms
may have some sort of
cephalization
Invertebrate characteristics

Reproduction + Development


Capable of both sexual + asexual
Some are hermaphrodites

Organism that produces both male + female gametes


Indirect development


Ex. Earthworm
Larval stage - change of appearances
Direct development


No larval stage
Animal is born or hatched – no change in appearance
Let’s look at these two…
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Indirect

Direct
Vertebrate characteristics


All vertebrate classes, except fish, spend part
or all of their life on land
Categories for terrestrial adaptations:


Support of body
Conservation of water
Vertebrate Characteristics – highlights

Have the following:




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


Body support – endoskeletons (backbone/vertebrae)
Body covering – integument
Gas exchange – lungs/gills
Circulatory - multichambered heart
Digestive – gut (mouth to anus) = 23 ft long in humans
Excretory – kidneys
Nervous – highly organized brains
Reproduction – fertilization of egg (zygote)
Development – direct development, except amphibians