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Zoology
Study Sheet
Know these important facts.
1. Today, the most generally accepted classification system contains six kingdoms
of living things: archaea, eubacteria, protists, fungi, plants, and animals.
2. Vertebrates are animals with a backbone.
3. Invertebrates are animals without a backbone.
4. Organisms that can make their own food through the process of photosynthesis
are called autotrophs. Organisms that cannot make their own food are a called
heterothrophs.
5. There are 9 major phyla in the animal kingdom: (See the 9 phyla chart distributed
earlier in the study zoology.)
a. Poriferans – animals with pores (sponges)
b. Cnidarians – stinging celled animals
c. Platyhelminthes – flatworms
d. Nematodes – round worms
e. Annelids – segmented worms
f. Mollusks – soft-bodied animals
g. Arthropods – animals with joined feet
h. Echinoderms – spiny-skinned animals
i. Chordates – animals with a dorsal nerve chord, notochord, and gill slits at
some point in their lives
Sponges:
1. Sponges belong to the phylum Porifera. Sponges are the simplest invertebrates.
2. Their bodies are covered with openings called pores.
3. They have no specialized tissue. They cannot move (sessile).
4. Collar cells (choanocytes) have flagella which move water and nutrients in
through openings called ostia and move wastes out from openings called oscula.
5. Sponges are thought to be an evolutionary dead-end.
6. Sponges reproduce sexually by releasing eggs and sperm cells and asexually by
budding. (Asexual reproductions involves only one parent.)
7. Some sponges have tiny glass or shell-like support structures called spicules in
addition to a fibrous structure made of spongin. (This sponging structure is what
people use for washing.)
8. Examples: Finger sponge, vase sponge
Cnidarians:
1. Cnidarians are the stinging-celled animals.
2. Cnidarians have muscles and nerves. They can move.
3. They have a hollow central cavity called a coelom,
4. They have one opening called the mouth. Food enters through the mouth, and
wastes leave through the mouth.
5. Cnidarians (called coelenterates in older books) have structures called
nematocysts (stinging cells) on their tentacles for defense and for stunning or
killing their prey. Cnidarians have two basic shapes the vase-shaped polyp and
the upside-down bowl-shaped medusa.
6. Corals are polyp-shaped cnidarians which live in colonies. Corals create the
structures known as reefs by producing calcium carbonate cups in which they
live.
Examples: jellyfish, sea fans, coral, anemones, hydra.
Worms:
1. There are three main groups of worms: flatworms, roundworms, and segmented
worms.
Flatworms:
2. Flatworms have flat bodies. Other than being flat, worms in the phylum
Platyhelminthes display many different traits.
3. Planaria live under rocks in streams and ponds. They have eyespots for detecting
light, but they prefer to live in dark areas. They have a tube-like mouth in the
middle of their arrow-shaped bodies. They eat dead animals and plants. They have
a digestive systems, nerves and muscles. Planaria can regenerate (regrow) their
bodies after being cut.
4. Another kind of flatworm is the tapeworm. Tapeworms are parasites that live in
the digestive systems of other animals. They have no digestive system. They have
a head (scolex) equipped with suckers and hooks that they use to hold onto the
intestinal lining of their host.
Roundworms:
1. Roundworms belong to the phylum Nematoda. Many nematodes live in the soil
and eat insects, microbes, and plants. Others are parasites living in the intestines
and other areas of their host’s body. Roundworms have a tube-within-a-tube
body design with a mouth at one end and an anus at the other. Roundworms
can be either male or female. Examples: hookworm, Trichinella worm, pin
worm.
Segmented worms:
1. Segmented worms are called annelids. They have segmented bodies. They live
in soil or fresh or salt water. Annelids also have a tube-within-a-tube
construction. They have 5 small hearts and a circulatory system, a nervous
system with a small brain, digestive system. Segmented worms are
hermaphrodites. They contain both male and female sex cells. They exchange
sperm when they mate. The reproductive structure is called a clitellum.
Examples: earthworm, leech, clam worm
Mollusks:
1. Mollusks are soft-bodied animals that belong to the phylum Mollusca. Mollusks
can have either one shell or two external shells or no shell. They could have
either an internal shell or no shell. Examples: 1 external shell - snail, 2
external shells – clam, no external shell – slug; 1 internal shell – squid, no
internal shell – octopus
2. Some mollusks have a thick muscular foot on which they move like a snail,
open and close their shells like a scallop or bury themselves in the mud like a
clam. Other mollusks have a set of tentacles with sucker disks for holding onto
prey.
3. Mollusks are covered with an extra layer of skin called the mantle. In shelled
mollusks, the mantle produces the shell material from special glands.
4. Gastropods (snails & slugs) and cephalopods (octopuses and squid) have a
rasping, file-like tongue called a radula. The bivalves (clams, oysters, scallops,
mussels) which are filter feeders do not. They get their food as water passes over
their bodies.
Arthropods
1. Arthropods have an exoskeleton, a segmented body (body in sections), and
jointed appendages (limbs/legs/antennae in sections that can bend).
2. An exoskeleton is a rigid outer covering.
3. The process by which arthropods shed their exoskeleton as they grow is called
molting.
4. Arthropods have an open circulatory system, or one in which the blood is not
contained within small tubes. Instead, the blood is pumped by a heart
throughout the spaces within the arthropod’s body. An arthropods blood carries
food nutrients but not oxygen.
5. The phylum of arthropods is divided into three main groups (classes): insects
like bees, beetles & butterflies, arachnids like spiders, scorpions, mites &
ticks, and crustaceans like crabs, barnacles, lobsters & shrimp. Two other
important arthropod groups are the millipedes and centipedes.
Crustaceans:
Crustaceans have a very hard exoskeleton, two pairs of antennae, five or more
pairs of legs, and mouthparts used for crushing a grinding food. Most
crustaceans have a three part body consisting of a head, thorax, and abdomen.
Crustaceans breathe using feathery gills.
Arachnids:
The bodies of arachnids are divided into two main parts: a cephalothorax
(head/chest) and an abdomen. Arachnids have four pairs of legs and no
antennae. Arachnids breathe using book lungs.
Insects:
Insects have three body parts: head, thorax (chest) & abdomen. Insects have
three pairs of legs. Insects have wings and antennae. Air enters their bodies
through openings in their abdomens called spiracles. Oxygen is delivered to the
cells by means of air tubes. Insects have both compound and simple eyes.
Some insects like bees and termites are called social insects. They cannot
survive on their own. Each one has a job to do for the benefit of the whole
group (hive/colony).
Metamorphosis: Arthropods such as insects and crustaceans undergo dramatic
changes as they grow from their youthful to their mature stages.
Metamorphosis is defined as the changes an animal undergoes as it develops.
(Amphibians also undergo metamorphosis.)
Complete Metamorphosis: A four stage process of development from egg to
larva to pupa to adult.
Incomplete Metamorphosis: The young look very much like the adults after
hatching from an egg. There may be some slight differences such as the absence
of wings.
Pheromones: Insects are known for having extremely powerful chemicals
called pheromones which they give off to attract mates. There is currently a
great deal of research on pheromones. Many animals give off these chemicals.
Centipedes and millipedes:
Centipedes are carnivores or flesh eaters. They are active hunters which inject
their prey with poison through their claws. Centipedes have one set of legs on
each section of their bodies.
Millipedes are shy plant-eaters (herbivores). They have two sets of legs on each
section of their bodies. Millipedes and centipedes do not have waterproof
bodies like other arthropods. You are most likely to find them under rocks and
other damp places to prevent water loss.
Echinoderms:
1. Echinoderms are invertebrates with rough, spiny skin, an internal skeleton, a
five-part body design, a water-vascular system, and tube-feet.
2. The name echinoderm comes from the Greek language. It means spiny skin.
3. Echinoderms are relatively advanced organisms that show radial symmetry.
4. In order to operate the water-vascular system, an echinoderm pulls water into
its body through an opening at the top of its body. Water is forced into a
system of canals and into its tube-feet. When filled with water, the tube feet
can move an echinoderm or hold onto its prey with a suction-like grip.
Examples of echinoderms include: starfish (sea stars), sea cucumbers, sea biscuits,
sand dollars, and sea urchins.
Chordates:
1. Chordates are animals that have a notochord, a nerve cord, and gill slits in their
throat area at some point in their lives.
2. The phylum name comes from the notochord, a flexible rod that supports the
animal’s back.
3. Some chordates, like the lancet, keep the notochord all their lives. Other primitive
chordates, such as tunicates, have a notochord as larvae, but not as adults.
4. Vertebrates are a subgroup of the phylum of chordates.
5. In vertebrates, part or all of the notochord is replaced by a backbone.
6. A few vertebrates, like sharks and rays, have backbones made of a soft bone
material called cartilage. Most vertebrates have a backbone made of hard bone.
7. All chordates have a nerve cord that runs down their back – a spinal cord is a
nerve cord. The nerve cord is the connection between the brain and the nerves.
Advanced chordates have a nerve cord that runs down their backs. This
allows messages to travel back and forth from all parts of the body to the brain
and back out to the body. (Other animals – crustaceans and worms, for example,
have nerve cords, but these do not run down their backs.
8. Chordates have slits in their throats. These are called pharyngeal gill slits. Fish
keep these slits all their lives, amphibians lose them as adults, reptiles, birds, and
mammals lose their gill slits before birth.
9. Backbones are formed by many similar bones called vertebrae that are lined up
in a row, like beads on a string. Joints between the vertebrae give the vertebral
column flexibility. Each vertebra has a hole in it that allows the spinal cord to
pass through it.
10. A vertebrate’s backbone is part of an endoskeleton or internal skeleton.
11. The job of the endoskeleton is to support and protect the body, give it shape,
and provide a place for muscles to attach.
12. A vertebrate’s endoskeleton includes the backbone, the skull, and the ribs.
13. The job of the skull is to protect the brain and sense organs.
14. The job of the ribs is to protect the heart, lungs and some other internal
organs.
15. Many vertebrates also have limbs – arm and leg bones adapted for a variety of
movements.
16. Animals with internal skeletons can grow larger than animals with
exoskeletons or no skeletons at all. An endoskeleton grows as the animal grows
and doesn’t have to be molted. An endoskeleton also protects the body against the
downward pull of gravity.
17. There are seven groups (orders) of vertebrates: jawless fish, cartilage fish,
bony fish, amphibians, reptiles, birds, and mammals.
18. Most fish, amphibians, and reptiles maintain a body temperature that is close to
the temperature of their environment. These animals are called “cold-blooded” or
ectothermic animals.
19. Birds and mammals have a stable temperature that is usually much warmed than
the temperature of their environment. These animals are called “warm-blooded”
or endothermic animals.
20. Endotherms have many adaptations for maintaining their internal body
temperature. Fur and feathers keep endotherms warm on cool days. Sweat glands
keep bodies cool on hot days. Because endotherms can keep their body
temperature stable, they can live in a greater variety of environments than
ectotherms can.