Transcript biol1030_kingdom_animalia_invertebrates

Kingdom Animalia
(Invertebrates)
Characteristics of Animals
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Multicellular
Eukaryotic
Heterotrophic consumers
Most are motile, but some are sessile
Most consist of cells that are organized
into tissues and organs
• Most reproduce sexually
Habitats of Animals
• Terrestrial—live on land
• Aquatic—live in water
– Freshwater—live in water that is not salty
(ex. ponds, lakes, streams, rivers)
– Marine—live in salt water (ex. oceans)
Classification of Animals
• Invertebrates—animals without a
backbone (95 % of animals)
• Vertebrates—animals with a backbone
(5 % of animals)
Types of Body Symmetry
• Asymmetry—have no symmetry (ex.
sponges)
• Radial Symmetry—has parts arranged
around a central axis; any plane passing
through the central axis divides the animal
into halves that are mirror-images of one
another (ex. jellyfish, starfish)
• Bilateral Symmetry—the right and left half of
the animal are mirror-images of each other;
animals with this type of symmetry generally
have cephalization, a concentration of
nervous tissue in the head region (ex. worms,
Anatomical Terminology
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Dorsal—the back surface of an animal
Ventral—the underside of an animal
Anterior—the front end of an animal
Posterior—the rear end of an animal
Lateral—the sides of an animal
Medial—along the midline of an animal
Primary Animal Phyla
• Porifera—sponges
• Cnidaria—jellyfish, coral, Portuguese Manof-War, hydra
• Platyhelminthes—flatworms (tapeworms,
flukes, planarians)
• Nematoda—roundworms (pinworms,
hookworms)
• Annelida—segmented worms (earthworms,
leeches)
Primary Animal Phyla
(continued)
• Mollusca—snails, slugs, octopus,
squids, clams, oysters
• Arthropoda—insects, spiders,
scorpions, crayfish, crabs
• Echinodermata—starfish
• Chordata—fish, frogs, snakes, turtles,
lizards, birds, dogs, cats, horses,
humans
Phylum Porifera
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“Pore bearers”, the sponges
Have no definite shape or symmetry
Have no tissue organization
Most are marine, but some are
freshwater
• Adult sponges are sessile; larvae are
free-swimming
Phylum Porifera (continued)
• The body of a sponge is shaped like a
sac; the inside is a hollow cavity
• Sponges have a large opening at the
top of the cavity called an osculum (no
mouth)
• The body of a sponge has numerous
tiny pores, through which water moves
into the animal; the sponge gets its food
and oxygen from this water
Phylum Porifera (continued)
• Sponges are “filter feeders”; as water moves
into the sponge through the pores, it is filtered
of small particles of food
• Collar cells are cells that line the inner body
cavity; they have flagella which beat to draw
water through the sponge and out the
osculum, filtering the water in the process
• Spicules are needle-like structures that
support the soft material of a sponge
Phylum Porifera (continued)
• Sponges can reproduce either asexually or
sexually
• During asexual reproduction, a small growth,
or bud, can break off the main part of the
sponge, attach to a substrate, and eventually
grow into a separate new sponge
• During sexual reproduction, specialized cells
can develop into either sperm or eggs; the
sperm swim out of the osculum and into
another sponge; there they fertilize eggs; the
larvae swim out of the osculum to become
new sponges
Phylum Porifera (continued)
• Sponges are hermaphroditic, which
means that they produce both sperm
and eggs
• Most have the ability to regenerate;
when cells of a sponge are separated
from one another (as when they are
injured), they can reorganize and form a
new sponge
Phylum Cnidaria
• Animals with stinging cells
• Jellyfish, Hydra, Obelia, coral, sea
anemone, Portuguese Man-of-War
• Most are marine
• Have radial symmetry
• Have some tissue organization
Phylum Cnidaria
(continued)
• There are two main body forms found in
cnidarians:
– Polyp—cylindrical, usually sessile animals
which have their mouths directed upwards
and tentacles surrounding it
– Medusa—generally free-floating, umbrellashaped animals which have their mouths
directed downwards and tentacles hanging
down around it
Phylum Cnidaria
(continued)
• Some cnidarians exist only as polyps; some
exist only as medusae; others alternate
between the two forms
• Some cnidarians exist singly; some exist as
colonies of animals
• Cnidarians can reproduce asexually (by
budding) or sexually (by production of
gametes)
Phylum Cnidaria
(continued)
• Cnidarians have stinging cells which are
used in capturing prey; when
stimulated, the cells poison/paralyze the
prey so it can be eaten
• The mouth of the animal leads into a
cavity where digestion occurs
• Wastes are expelled out the mouth
Phylum Platyhelminthes
• Flatworms (ex. planarians, flukes, and
tapeworms)
• Have flattened bodies, bilateral
symmetry, and cephalization
• Have distinct tissue layers
• Simplest animals with organs
Planarians
• Free-living flatworms
• Freshwater (found in ponds, lakes, and
streams)
• Scavengers
• Hermaphroditic
• Breathe through skin
• Regenerate well
Planarians (continued)
• Mouth—only body opening; located
halfway down the body on the ventral
surface; can project its pharynx (throat)
out the mouth to suck up food
• Intestines—digest food
• Eyespots—sensory structures used for
detecting light; planarians prefer
darkness
Flukes
• Parasitic flatworms (internal
parasites); blood flukes and liver flukes
can infect humans
• Oral suckers enable the worm to attach
to the intestines of the host
• Hermaphroditic; body primarily consists
of reproductive organs
Life Cycle of a Fluke
• Eggs are released from an infected individual
with wastes; in some areas of the world,
human wastes are used as fertilizer for crops
• Eggs hatch into larvae in swampy, marshy
land areas (mainly in Asia and the tropics)
• Sometimes snails serve as intermediate
hosts
• Larvae may enter humans through the skin
(of the feet usually)
• Larvae then pass through the bloodstream to
the intestines, where they attach, feed, and
Tapeworms
• Parasitic flatworms (internal parasites);
beef tapeworms, fish tapeworms, and
pork tapeworms can infect humans
• The tapeworm’s head has hooks and
suckers which enable the worm to
attach to the host’s intestine
• The body consists of a long chain of
segments
Tapeworms (continued)
• Hermaphroditic; each segment contains
reproductive organs
• Segments that are farthest from the
head contain mature eggs; these are
shed daily and released from the body
of an infected individual with the feces
Life Cycle of a Tapeworm
• If a human eats poorly cooked beef, pork, or
fish that contains larvae, infection can occur
• The cow, pig, or fish (intermediate hosts) can
be infected by eating food which contains the
tapeworm eggs
• Once inside the animal, the eggs become
embryos, and then larvae; the larvae encyst
in muscle, which is the part eaten by humans
• When a human eats the infected meat,
digestive juices break down the cysts and
release the larvae
Life Cycle of a Tapeworm
(continued)
• The larvae attach to the intestines, where
they feed, grow, and reproduce, when mature
• Tapeworms may grow up to 50 feet long and
may live within a host for up to 10 years
• Symptoms of infection include weight loss,
increased appetite, and occasionally pain and
discomfort
Phylum Nematoda
• Roundworms (ex. hookworms, pinworms,
heartworms)
• Found almost everywhere—in soil,
freshwater, and saltwater; many are parasites
• Have a tube-like body and bilateral symmetry
• Distinct tissue layers and definite organs
• Usually separate sexes; males are generally
smaller in size than females
Phylum Nematoda
(continued)
• Complete digestive tract with a mouth at one
end and an anus at the other
• Body is covered by a tough cuticle, which is
a thickening of the epidermis that protects the
worm (from drying out); the cuticle is shed, or
molted, as the worm grows
• Beneath the epidermis is a layer of muscles
that allows the worm to move by thrashing
back and forth
Hookworms
• Internal parasites; live in the human intestine,
where they feed, mature, and lay eggs
• The eggs pass out of the body with the feces
• If human wastes are used as fertilizer, the
larvae develop in the soil
• They may enter a human through the skin
(usually by boring through the skin of the feet
as an individual walks on soil contaminated
with larvae)
• The larvae migrate through the body to the
intestine
Pinworms
• The most common parasitic worms
found in children
• May enter a human host if the individual
ingests eggs by eating with dirty hands
• Adult worms are about ½ inch long
• They live in the large intestine
Pinworms (continued)
• Female worms migrate to the host’s
anus (usually at night) to deposit eggs
• This causes itching, irritation, and
scratching, which spreads the eggs
• The eggs can even be spread in the air
to other people
• Some pinworm infections are mild;
some cause much intestinal discomfort
Phylum Annelida
• Segmented worms (ex. earthworms,
leeches, sandworms); have many body
segments
• Found in freshwater, marine, or
terrestrial habitats
• Have bilateral symmetry
Leeches
• Live in freshwater, but are also external
parasites
• May attach to the skin of a host with suckers
at each end of the body
• Suck blood, which is stored in pouches within
their bodies
• Secrete an anticoagulant which keeps blood
from clotting; leeches are occasionally used
in medicine
Earthworms
• Burrow in the soil using paired bristlelike structures; these structures are
found on the ventral surface of each
body segment
• Earthworms are important ecologically
because they aerate the soil as they
burrow
Earthworms (continued)
• Complete digestive tract with a mouth at
one end and an anus at the other
• Body is covered by a cuticle, which is
secreted by the epidermis and helps to
prevent the worm from drying out; the
epidermis also secretes mucus to
further prevent drying out
Earthworms (continued)
• Body wall consists of an outer layer of
circular muscles and an inner layer of
longitudinal muscles
• Respiration occurs through the skin
• Kidney-like structures that excrete liquid
wastes located in each body segment
Earthworms (continued)
• Digestive system is quite advanced; consists
of the following structures (in order from
anterior to posterior):
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Mouth—food (mixed with soil) enters here
Pharynx—throat; a passageway
Esophagus—a passageway
Crop—stores food
Gizzard—grinds food
Intestine—digests food; a passageway
Anus—eliminates wastes
Earthworms (continued)
• Circulatory system is also quite
advanced; consists of the following
structures:
– 2 main blood vessels, one dorsal and one
ventral
– 5 pairs of arched blood vessels that
connect the other two vessels; these
vessels pump blood, so they make up the
“heart”
Earthworms (continued)
• Nervous system consists of:
– Ventral nerve cord
– Paired masses of tissue called ganglia;
this is the “brain”
Earthworms (continued)
• Hermaphroditic
• Reproductive system consists of:
– Clitellum—a thickened band of the
epidermis that secretes a mucus
substance, which is used to hold two
worms together during sexual reproduction
– Seminal vesicles—produce sperm
– Seminal receptacles—receive and store
sperm
Phylum Mollusca
• Soft-bodied animals
• Includes snails, slugs, clams, scallops,
oysters, octopuses, squids
• Many are marine, but some are
freshwater, and some are terrestrial
• The body of most mollusks is covered
by a shell
Structure of Mollusks
• A muscular foot is used for movement; in the
octopus and squid, the foot is divided into tentacles,
which are also used for food-getting
• The visceral mass contains most of the internal
organs
• The mantle is a heavy fold of tissue which covers the
visceral mass; it contains glands that secrete the
shell
• Gills are used for respiration in aquatic mollusks
Structure of Mollusks (cont.)
• Mollusks have a digestive system
consisting of a mouth, esophagus,
stomach, intestine, and anus
• Many have an open circulatory
system, which consists of a heart,
blood vessels, and blood; in an open
system, though, the blood bathes the
body tissues directly by pooling in a
blood-filled cavity
Structure of Mollusks (cont.)
• Sexes are usually separate, and
fertilization generally takes place in the
surrounding water; most marine
mollusks pass through one or more
larval stages
Special Mollusk Features
• Bivalve mollusks are filter feeders; they get
food particles from the water they draw into
their bodies
• If a piece of foreign matter lodges between
the bivalve’s shell and mantle, a pearl can
form
• The mantle secretes the shell; the interior of
the shell is made of a substance called
mother of pearl; this substance surrounds
the foreign particle and forms a pearl
Special Mollusk Features
(cont.)
• Cephalopods (octopus and squid) are active,
predatory animals that move by jet
propulsion; they take in water, and then
force it out to push themselves through the
water
• The octopus has 8 tentacles; the squid has
10
• An octopus has no shell; the squid’s shell is a
hard, internal structure called a pen
Special Mollusk Features
(cont.)
• Cephalopods are active at night and in the
dark depths of the ocean; they have large,
well-developed eyes that can actually see
images (much as human eyes)
• Many cephalopods can change colors to fool
predators; some have ink sacs that release a
dark liquid that blinds predators
Phylum Arthropoda
• The most successful group of animals in
terms of number and types of habitats
• Animals with jointed appendages (walking
legs, swimming structures, claws, antennae,
specialized mouthparts)
• Includes insects, spiders, crayfish, crabs
Characteristics of
Arthropods
• Exoskeleton—a hard, external skeleton
that covers the entire body; provides for
muscle attachment, gives
support/structure to the body, protects
against drying out and predators;
periodically shed as the animal grows
by a process called molting
Characteristics of
Arthropods (cont.)
• Body segmentation; insects have 3
main body regions; spiders have 2
• Open circulatory system
• Nervous system consists of a nerve
cord and ganglia (the “brain”)
Charcteristics of Arthropods
(cont.)
• Well-developed sense organs such as
antennae and compound eyes
• Respiratory system consists of gills in
aquatic animals and lung-like structures
in terrestrial forms
Arachnids
• Includes spiders, daddy longlegs, scorpions,
ticks, mites, and chiggers (the larval form of a
red mite)
• Body consists of 2 main body regions
• 4 pair of walking legs (8 legs total)
• Have fang-like structures used in getting prey
• Have appendages used to hold and chew
food; most arachnids feed on insects and
other arthropods
Arachnids (cont.)
• Respiration is usually by book lungs
• Many spiders have silk glands in their
abdomens which secrete a protein substance
used in making webs; spinnerets are
structures used to spin the substance into
webs, which are used for trapping prey and/or
as nests
• All spiders have poison glands used in
capturing food, but only a few produce
poisons that are toxic to humans
Poisonous Spiders in Our
Area
• Black Widow—produces a neurotoxin
that interferes with nervous system
transmission
• Brown Recluse—produces a
hemotoxin that causes tissues to die
Centipedes
• “100-legged animals” (they don’t really have
that many legs)
• Terrestrial; found under rocks or wood
• Have a flattened body, a head, an elongated
trunk with many segments, and one pair of
legs per segment
• Carnivorous; feed on insects and other small
animals; have poison claws just behind the
head
• Move rapidly
Millipedes
• “1000-legged animals” (they also don’t really
have that many legs)
• Terrestrial; also found under rocks or wood
• Have a cylindrical body, a head, an elongated
trunk with many segments, and two pair of
legs per segment
• Herbivorous; feed on living and decomposing
plants
• Move slowly
Crustaceans
• Includes lobster, crayfish, shrimp, and
crab
• Mainly marine, but a few freshwater
• Body consists of 2 main body regions
• 5 pair of walking legs (10 legs total; 2
are claws)
• Have mandibles, or jaws, for biting and
grinding food
Crustaceans (cont.)
• Have 2 pair of sense organs for touch
and taste: antennae and antennules
• Have large eyes
• Have appendages used to hold food
• Respiration is with gills
• Green glands are excretory organs
found in the head
Crustaceans (cont.)
• Nervous system consists of ganglia
and a nerve cord
• Sexes usually separate; the male uses
specialized appendages to transfer
sperm to the female; the eggs hatch into
larvae, which go through a series of
molts and stages before reaching
adulthood
Insects
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The most successful animals on Earth
Most are terrestrial, but some are aquatic
Have complex mouthparts
Body consists of 3 main body regions
3 pair of legs (6 legs total)
Usually have 2 pair of wings
Have 1 pair of antennae
Insects (cont.)
• Have both simple eyes and compound
eyes
• Respiration is with tracheae, or air
tubes
• Sexes separate; fertilization is internal
Insects (cont.)
• Development is called metamorphosis
because if consists of a series of
stages:
– Incomplete metamorphosis
• egg nymphadult
– Complete metamorphosis
• egglarvapupaadult
Insects (cont.)
• Many insects live in colonies/societies,
with each member carrying out a
specific function (ex. Bees and ants)
• Insects are not all harmful pests (ex.
Bees produce honey; other animals
feed on insects; some insects
decompose dead organisms and
wastes)
Phylum Echinodermata
• Spiny-skinned animals
• Includes starfish, sand dollar, sea
urchin, brittle star, and sea cucumber
• Have bilateral symmetry as larvae;
radial symmetry as adults
• All are marine
Phylum Echinodermata
(cont.)
• Have an internal skeleton, or endoskeleton
• Move by use of a water vascular system,
consisting of a network of canals through
which water circulates; branches of these
canals lead to numerous tube feet, which are
used for movement and food-getting
• Very little development of the nervous,
circulatory, excretory, and respiratory
systems; no brain or heart
Phylum Echinodermata
(cont.)
• Digestive system is the most advanced
system
• Usually separate sexes; sperm and
eggs are released into the water, where
fertilization occurs
• Starfish have an excellent ability to
regenerate lost arms