Transcript File

Animal Kingdom Invertebrates
• Members of the domain Eukarya, kingdom Animalia
• Heterotrophic by ingestion
• Most often move by muscle fiber contraction
• Multicellular with specialized cells that form tissues &
organs
• Life cycle where adult is diploid
• Usually undergo sexual reproduction that produces a
developing embryo
Animals
• Believed to have evolved from protistan ancestor 700
million years ago
• Most animal phyla are invertebrates
– Lack endoskeleton of bone or cartilage
– Lack a backbone or vertebral column
• Phylum Chordata is the only phylum with a endoskeleton
of bone or cartilage
– Considered vertebrates
– Vertebral column replaces notochord
Level of Organization
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Three levels of
organization in animal
kingdom: cellular,
tissue, & organ levels.
There are 3 primary
germ layers that
develop into specialized
tissues that make up
organism:
1. Endoderm
2. Mesoderm
3. Ectoderm
Type of Body Plan
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There are 2 types of body
plans in animal kingdom:
Sac plan
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Incomplete digestive system
Has a single opening where
food enters & wastes exit
Ex. Hydra
Tube-within-a-tube plan
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Inner tube is digestive tract
Outer tube is body wall
Has two separate openings
Food enters in one opening
with wastes exit a different
hole
Ex. Humans, crayfish
Type of Symmetry
• Asymmetrical: no
symmetry
– Ex. Some sponges
• Radial symmetry:
animal is organized
circularly like a wheel.
– Ex. Cnidarians
• Bilateral symmetry:
definite right & left halves
– Longitudinal cut produces
mirror images
– Ex. Humans
• Cephalization= sensory
organs & brain localized
at anterior end (head)
Type of Body Cavity
• Coelom: body cavity that
contains animal’s internal
organs
Ex. Earthworms, humans
• Acoelomate: no body
cavity
Ex. Flatworms
• Pseudocoelom: body
cavity that is partially
lined with mesoderm
Ex. Roundworms
Body Cavities Cont.
• The importance of body
cavities include:
– Provide a space in which
internal organs can be
placed
– Allow body systems to
work efficiently because
they are not compressed
– Allow room for internal
organs to develop &
expand
– May contain fluids involved
in internal transport, or
carry waste or food from
one part of the body to
another
Two Major Groups of Coelomates
• Based on embryonic
development
• If first embryonic opening
becomes a mouth the animal is
a protostome
Ex. Clams, earthworms,
crayfish
• If second opening becomes a
mouth the animal is a
deuterostome
Ex. Starfish, humans
Segmentation
• Repetition of body parts
along the length of the
body
• Animals can be
segmented or
nonsegmented
• Leads to specialization of
parts
Sponges
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Phylum Porifera
Aquatic, mostly marine
Vary in size, shape, color
Multicellular but lack
organized tissues
Have cellular level of
organization
Outer layer of cells made
of flattened epidermal
cells (contractile fibers)
Middle layer of cells is
semifluid matrix (ameboid
cells)
Inner layer has flagellated
cells called collar cells
Sponges cont.
• The flagella on collar cells produce water currents that
flow through pores into central cavity out the osculum
• Sessile filter feeders (digest food within cells)
• Pores in the walls and microvilli making up part of the
collar cells strain food from water
• Food passes from collar cells food vacuoles
ameboid cells to all cells
• Reproduce asexually by any of these methods:
fragmentation, regeneration, gemmule formation, or
budding
Sexual Reproduction in Sponges
• Ameboid cells produce the sex cells and spicules (small
needle-shaped structures)
• Sperm are released through osculum
• A different sponge will draw in the sperm through its
pores where it will fertilize eggs within the body
• Most sponges are hermaphoditic (contain male & female
sex organs)
• Sponges do NOT usually self-fertilize
• After fertilization, zygote becomes flagellated larva that
swim to new location
Cnidarians: True Tissues
• Phylum Cnidaria
• Multicellular, tubular, or
bell-shaped animals
found in shallow coastal
waters
• Radially symmetrical
• Have tissue level of
organization
• Cnidocytes are
specialized stinging cells
• Nematocysts
threadlike fibers found in
cnidocytes that are used
to capture or sting prey
Cnidarians cont.
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Examples: sea anemone,
jellyfish, Hydra, corals
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Two basic body forms:
Polyp= sessile stage
Medusa= sexual, motile
stage; has a lot of mesoglea
(jellylike
material); produces sperm &
egg
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Alternates between poly &
medusa stage throughout
life cycle
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Zygote develops into ciliated
larva capable of dispersal
Hydra
• Class Hydrozoa
• Freshwater cnidarian found attached to underwater plants
& rocks
• Has a sac body plan (one opening serves as mouth/anus)
• Only have the poly stage (NO medusa stage)
• Body composed of:
– Epidermis: outer most tissue layer
– Mesoglea: middle tissue layer
– Gastrodermis: inner tissue layer made up (of gastrodermal cells)
• Contain circular & longitudinal muscle fibers
– Body can contract or extend
– Can use tentacles that ring the mouth to reach out & grasp prey
• Contain nerve cells & a nerve net (primitive brain)
Hydra cont.
• Gastrovascular cavity (found in all cnidarians)
– Carries on digestion using food vacuoles in gastrodermal cells
– Acts as circulatory system by distributing food and gases
• They can reproduce sexually or asexually
– Sexual reproduction involves an ovary or a testis
developing in the body wall
– Asexual reproduction involves regeneration and budding
bud
Flatworms: Bilateral Symmetry
• Phylum Platyhelminthes
• Have three germ layers (endoderm, mesoderm,
ectoderm)
• Acoelomate= no coelom (body cavity)
• Have muscles and excretory, reproductive and digestive
systems
• Lack respiratory and circulatory systems
– Body is flat and thin
– Diffusion is used to pass oxygen and other substances cell to cell
Planarians: Flatworms
• Mostly freshwater found in
lakes, ponds, streams, and
springs
• Feed on small living or dead
organisms (worms)
• Excretory system consisting
network of interconnecting
canals
• Flame cells have cilia that
beat to keep water moving
to excretory pores
Planarians cont.
• Have ladder-like nervous
system
– Small anterior brain with two
lateral nerve cords joined by
cross branches
– Have cephalization (brain
localized in anterior head)
– Have light sensitive eyespots
• Have chemosensitive organs
located on auricles
• Have three muscle layers that
allow varied movement
• Possess a ciliated epidermis
that enables gliding along a
mucus film
Planarian cont.
• Can reproduce both sexually and asexually
• Hermaphroditic
• Can cross fertilize where the penis of one worm is
inserted into the genital pore of another
– Exchange of sperm takes place
– Fertilized eggs hatch in 2-3 weeks
• Asexual reproduction occurs by regeneration
Parasitic Flatworms
• There are 2 classes: 1) tapeworms (Cestoda) & 2) flukes
(Trematoda)
• Tapeworms as adults are endoparasites to several
vertebrates
• Have tough integument (body covering) to protect from
host’s harsh digestive system
Parasitic Flatworms
• Have well-developed
anterior region called
the scolex
– Scolex has hooks
for attachment to
intestinal wall of
host
– Have suckers for
feeding
Parasitic Flatworms
• Proglottids= series of
reproductive units with a
full set of male & female
sex organs
• Each proglottid fertilizes
its own eggs
– Immature proglottids
located behind scolex
– Mature proglottids are
farther away
Flukes
• Endoparasite of several
vertebrates
• Nonciliated integument
(skin)
• Oral suckers found at
anterior end
– Surrounded by sensory
papillae
– Used to attach to host
• Nervous & digestive
systems are reduced
• Poorly developed sense
organs
• Most are hermaphroditic
Roundworms: Pseudocoelomates
• Phylum Nematoda
• Have tube-within-a-tube body
plan (have mouth & anus)
• Have a fluid-filled body cavity
called pseudocoelom
– Provides space for the
development of organs
– Substitutes for circulatory
system
– Provides type of skeleton
called a hydrostatic skeleton
• Hydrostatic skeleton:
fluid-filled interior that supports
muscle contraction
• Bilaterally symmetrical
• Colorless, non-segmented
• Live in freshwater, marine, &
soil habitats
• Can be free-living or parasitic
Ascaris: roundworm
• Females are larger than
males
• Move by whiplike motions
• Most commonly parasites
of humans & pigs
• Female can produce over
200,000 eggs daily
• Eggs are eliminated in
host feces
• Eggs enter host by
uncooked veggies, dirty
fingers or ingested fecal
material
• Eggs hatch in intestines
into juvenile worms
Other Roundworms
• Trichinosis is an infection
caused by Trichinella
spiralis
– Caused by eating
undercooked pork that
contains encysted larvae
– Adult female burrows in
intestinal wall & deposits
larva
– larva move to bloodstream
& encyst in skeletal
muscles
• Symptoms include
digestive problems,
fatigue, fever, aching
joints, muscle pain
Molluscs: Coelomates
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Phylum Mollusca (make up second largest phylum)
Bilateral symmetry, three germ layers, organ level of
organization
Tube-within-a-tube body plan
Three distinct parts all molluscs have:
Visceral mass= soft-bodied part that contains
internal organs (digestive tract, paired kidneys,
reproductive parts)
Foot= strong muscular portion used for locomotion
Mantle= membranous or muscular covering the
envelops the visceral mass; may secrete a shell
(exoskeleton)
Often have a rasping, tongue-like radula which has
teeth and is used to obtain food
Gastropods: Class Gastropoda
• Nudibranchs (sea slugs),
conchs, & snails
• Move by contracting muscular
foot
• May be herbivores or
carnivores
• Terrestrial, freshwater, or
marine habitats
• All but nudibranchs have a
univalve coiled shell
• May have gills (aquatic) or a
mantle with blood vessels that
acts as a lung
• Land snails are hermaphoditic
• Each snail inserts its penis into
each other’s vagina
• Fertilized eggs are deposited
externally without swimming
larvae
Bivalves: Class Bivalvia
• Clams, mussels, scallops, &
oysters
• Shells have 2 parts
• Shells are secreted by the
mantle
– Composed of protein, calcium
carbonate, mother-of-pearl
– Pearls form when foreign
matter is trapped between
mantle & shell
• Adductor muscles hold shells
together
• Gills are used for gas
exchange
Bivalves: Class Bivalvia
• Clams are filter feeders
• Has a 2 chambered heart with a pericardial cavity
• Has an open circulatory system because blood is
not contained in blood vessels after it leaves heart
• Inside of organs, blood flows through sinuses (spaces)
• Clams lack cephalization
• Move by extending muscular foot & pulling body after it
• Digestive system includes a mouth, esophagus, stomach
and intestines, ending in an anus
• Kidneys remove liquid wastes
• Sexes are separate
• Clams have a larval stage
• Marine clams have trochophore larva
Annelids: Segmented Worms
• Phylum Annelida that includes
marine worms, leeches, &
earthworms
• Most are marine
• Segments are divided by septa
• Well-developed coelom that is
fluid-filled and acts as a
hydrostatic skeleton
– Permits each body segment to
move independently
– Locomotion involves
contraction & expansion of
each segment
• Tube-within-a-tube body plan
with specialized digestive tract
– Includes a pharynx,
esophagus, crop, gizzard,
intestine, & accessory glands
Annelids: Segmented Worms cont.
• Have a closed circulatory system with blood
vessels that run entire length of body & branch to every
segment
• Nervous system consists of a brain connected to a
ventral solid nerve cord
• Ganglia occur in each segment
• Excretory system consists of paired nephridia in most
segments
– Nephridium: tubule that collects waste material and excretes it
through opening in body wall
• Setae are bristles that anchor the worm & help it move
Annelids: Segmented Worms cont.
• Earthworms are hermaphroditic
– Male organs are testes, seminal vesicles, sperm ducts
– Female organs are ovaries, oviducts, & seminal receptacles
• When mating, 2 worms lie parallel facing each other in
opposite directions
– Clitellum secretes mucus to prevent sperm from drying out as it
passes between 2 worms
– After worm separate, clitellum produces a slime tube
– Muscular contractions move eggs & sperm together and
fertilization to occurs
– Slime tube protects developing worms
– There is no larval stage
Arthropods: Jointed Appendages
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Phylum Arthropoda that is divided into 3 subphyla
Subphylum Crustacea: barnacles, shrimps,
lobsters, & crabs (mostly marine)
Subphylum Uniramia: insects like bees, ants,
termites
Subphylum Chelicerata: arachnids such as
terrestrial scorpions, spiders, ticks, mites
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Have a jointed exoskeleton made of chitin
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Provides protection
Attachment for muscles
Locomotion
Prevents drying out
Arthropods: Jointed Appendages cont.
• Must molt or shed exoskeleton as they grow larger
– Secretes new exoskeleton before molting
• Segmented body often fused into head, thorax, and
abdomen
• Have specialized appendages for walking, swimming,
reproducing, eating, & sensory perception
• Well-developed nervous system with a brain & solid
nerve cord
– Head bear antennae & two types of eyes (compound & simple)
– Compound eye= composed of many complete visual units
that each operate independently
– Lens= focuses an image on light sensitive membranes that
contain photoreceptors for each unit
– Vision is good at detecting movement
Crustaceans
• Segmented animals with rigid
exoskeleton
• Have open circulatory system
• Usually have a pair of
compound eyes with five pairs
of appendages
• Green glands excrete
metabolic wastes through a
duct to outside of body
• Male crustacean deposits
sperm in female which holds
on to it until she lays eggs
• After eggs leave ovary, they
stick to swimmerets until they
hatch
• Blood is blue due to
hemocyanin which carries
oxygen
Arachnids: Class Arachnida
• Subphylum Chelicerata
• Most numerous are the spiders
• Bodies are divided into 2 parts: the cephalothorax & the
abdomen
• Have 1 pair of chelicerae, 1 pair of pedipalps, and four
pairs of walking legs
• Use chelicerae as fangs to inject poison to kill prey
• All spiders have venom, but not all are poisonous to
humans
• Silk is released through spinnerets to make webs or to
contain food
• Females can use silk to hold eggs
Arachnids: Class Arachnida
• Spiders use book lungs for
respiration
– Consist of folded
membranes that look like
pages in a book
– Folding increases surface
area for gas exchange
• Spiders reproduce sexually
• Male sperm cells are held in
seminal receptacle in female
• When it is time to lay eggs,
sperm is released on eggs
Insects
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Subphylum Uniramia is very numerous & diverse
All insects have the following features in common:
Body divided into 3 parts: head, thorax, abdomen
Head bears pair of sensory antennae, pair of
compound eyes, & several simple eyes
Abdomen contains most of the internal organs
Thorax bears 3 pairs of legs and the wings (either 1 or
2 pairs or no pairs)
Excretory system consists of malpighian tubules
Respiratory system begins with openings in
exoskeleton called spiracles
Air then enters tubules called tracheae
Air is pumped via muscular contraction of body wall
Differences between arachnids & insects:
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Arachnids have 8 legs; insects have 6 legs
Arachnids have 2 body segments; insects have 3
Insects have antennae, arachnids do not
Insects have wings attached to the thorax; arachnids
do not have wings
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Unique to insects is that they go through
developmental stages called a metamorphosis
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Incomplete metamorphosis: eggnymph (small adult) adult
Ex. Dragonflies, grasshoppers
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Complete metamorhosis: 4 stages egg, larva, pupa, adult
Ex. Butterflies, ants
Both insects and arachnids molt
Phylum Echinodermata
• Echinoderms
– Invertebrate animal group most closely related to
chordates (that’s us)
• Similar embryological development
• Deuterostome with second embryonic opening
forming the mouth
– Marine animals that do have an endoskeleton
• Consists of spine-bearing, calcium rich plates
• Spines stick out through skin
– Echino- (spiny)
derm- (skin)
Echinoderms cont.
• Most have pentamerous radial
symmetry
– Radial symmetry that can
be broken into 5 equal
parts
• Larva is a free-swimming filter
feeder
• Examples of echinoderms:
sea lilies, feather stars, brittle
stars, sea cucumbers, sea
stars, sea urchins
• Sea stars have an aboral side
or anus side (upper side) & an
oral (mouth) side on underside
• Have a well-developed coelom
Sea Stars cont.
• Have endoskeletal
plates that provide
protection
• Have pedicellariae
that keep surface free
of particles
• Have skin gills used
for gas exchange
• Lack respiratory,
excretory, &
circulatory systems
Sea Stars cont.
• Have tube feet
– Series of small suction discs found on oral surface
– Used for locomotion and food retrieval
• Most are carnivorous
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Mouth is located on underside
Feeds by pushing its cardiac stomach out
Stomach releases digestive enzymes on food
Digestion begins outside of body
Later partially digested food is brought into body
• Each arm contains a pair of digestive glands & gonads
(either male or female)
• Nervous system consists of central nerve ring & radial
nerves with light sensitive eyespot
Sea Stars cont.
• Have a water vascular system with tube feet
– Water enters through the madreporite on upper surface
– Water then moves through the arms to the tube feet
– Each foot moves by continually filling and emptying of water
• Reproduction is usually sexual
• Capable of asexual reproduction via regeneration
– Fragment must contain part of central disc