Transcript 33invertebrates

Chapter 33 Invertebrates
Phylum Porifera: Sponges
are sessile with porous
bodies and choanocytes
True Multicellular Org
Allows for specialization of cells
Intracellular digestion
Phylum Cnidaria: Cnidarians have radial symmetry, a
gastrovascular cavity, and cnidocytes
Two layers of cells that form TISSUES - cells that act as a functional unit
Gastrovascular cavity that allows for extracellular digestion - large food particles broken down so
that the gastrodermis can do intracellular digestion.
Simple nerve net forms nervous system - no brain
Hydra capturing prey
Budding a form of asexual reproduction is also seen
Batteries of
cnidocytes on the
tentacles defend the
animal or capture prey
Sea anemone
Soft Coral
Class Anthozoa
1. Phylum Platyhelminthes: Flatworms are
acoelomates with gastrovascular cavities
• There are about 20,000 species of flatworms
living in marine, freshwater, and damp terrestrial
habitats.
– They also include many parasitic species, such as the
flukes and tapeworms.
• Flatworms and other bilaterians are triploblastic,
with a middle embryonic tissue layer, mesoderm,
which contributes to more complex organs and
organs systems and to true muscle tissue.
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Class Tubularia
free living
flatworm
Tubularia
Planarian
Two way gut
ventral nerve cords
Cephalization - brain, eye spot at head
gastrovascular cavity
acoelomate
Schitstosoma
mansoni the
blood fluke
responsible for
schistosomiasis
has a complex
life cycle
The larvae infects snails,
the fluke infects humans
Class Trematoda
Tapeworms class
Cestoidea
the head (scolex) has
hooks and a sucker
the proglottids are
mainly made of sex
organs
2. Phylum Rotifera: Rotifers are
pseudocoelomates with jaws, crowns of
cilia, and complete digestive tracts
• Rotifers, with about 1,800 species, are tiny
animals (0.05 to 2 mm), most of which live in
freshwater.
– Some live in the sea or in damp soil.
• Rotifers have a complete digestive tract with a
separate mouth and anus.
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• The word rotifer, “wheel-bearer”, refers to the
crown of cilia that draws a vortex of water into
the mouth.
– Food particles drawn in by the cilia are captured by
the jaws (trophi) in the pharynx and ground up.
Fig. 33.13
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5. Phylum Mollusca: Mollusks have
a muscular foot, a visceral mass,
and a mantle
• The phylum Mollusca includes 150,000 known species
of diverse forms, including snails and slugs, oysters and
clams, and octopuses and squids.
• Most mollusks are marine, though some inhabit fresh
water, and some snails and slugs live on land.
• Mollusks are soft-bodied animals, but most are protected
by a hard shell of calcium carbonate.
– Slugs, squids, and octopuses have reduced or lost their shells
completely during their evolution.
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• Despite their apparent differences, all mollusks
have a similar body plan with a muscular foot
(typically for locomotion), a visceral mass with
most of the internal organs, and a mantle.
– The mantle, which secretes the shell, drapes over the
visceral mass and creates a water-filled chamber, the
mantle cavity, with the gills, anus, and excretory
pores.
– Many mollusks feed by using a straplike rasping
organ, a radula, to scrape up food.
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Mantle secretes
the shell
Radula is used
for rasping food
off of surfaces,
but can be
modified to bore
holes or tear
apart tough
animal tissue
Has trochophore
larvae a type of
ciliated larvae
They lack true
segmentation
• The basic molluscan body plan has evolved in
various ways in the eight classes of the phylum.
– The four most
prominent are the
Polyplacophora
(chitons),
Gastropoda
(snails and slugs),
Bivalvia (clams,
oysters, and other
bivalves), and
Cephalopoda
(squids, octopuses,
and nautiluses).
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Chiton class
Polyplacophora
Gastropoda is
the largest
molluscan class
During
embryonic
development it
undergoes
torsion which
results in its
asymmetrical
shape
bivalves
• The class Bivalvia includes clams, oysters,
mussels, and scallops.
• Bivalves have shells divided into two halves.
– The two parts are hinged at the mid-dorsal line, and
powerful adductor muscles close the shell tightly to
protect the animal.
– When the shell is open,
the bivalve may extend
its hatchet-shaped foot
for digging or anchoring.
Fig. 33.20
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Cephalopods
have reduced or
missing shells
the only
molluscan with a
closed circulatory
system
besides Ryan, the
most intelligent
invertebrate with
a well developed
nervous system
and brain
6. Phylum Annelida: Annelids are
segmented worms
• All annelids (“little rings”) have segmented
bodies.
• There are about 15,000 species ranging in length
from less than 1 mm to 3 m for the giant
Australian earthworm.
• Annelids live in the sea, most freshwater habitats,
and damp soil.
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Annelids have a true
coelom - which allows for
easier fluid movement
between organs
They have body
segmentation - each
segment can become
specialized
closed circulatory system
with hearts- blood with
hemoglobin
excretory tubes called
metanephridia collects
wastes from the blood
through a funnel called a
nephrostome and dumps
it outside through
nephridia pores.
Fan Worm
Polychaete worm is an Annelid
they have true body segmentation
they have parapodia used in locomotion and gas
exchange
• Until this century, leeches were frequently used
by physicians for bloodletting.
– Leeches are still used for treating bruised tissues
and for stimulating the circulation of blood to
fingers or toes that have been sewn back to hands or
feet after accidents.
Fig. 33.24d
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Phylum Nematoda: Roundworms are nonsegmented
pseudocoelomates covered by tough cuticles
complete digestive tract
Trichinella spiralis in pork muscle
In a true coelom, muscle
entirely lines the wall of
the body cavity allowing
for efficient movement of
material between organs
and also movement along
the length of the gut
BLASTULA
invagination
GASTRULA
Forms mouth
in
protostomes
NEURULA
Arthropods are segmented coelomates with
exoskeletons and jointed appendages
The diversity and
success of
arthropods is
largely due to three
features: body
segmentation, a
hard exoskeleton,
and jointed
appendages.
Peripatus or Walking worm may be the predecessor
of Arthropods
segmented but missing jointed appendages
Phylum Onychophoran
Trilobita were segmented but most were the same
- modern arthropods have fewer and more specialized segments
Crustaceans
03/07/06 -- Divers have discovered a new crustacean in the
South Pacific that resembles a lobster and is covered with
what looks like silky, blond fur, French researchers said
Tuesday.
Scientists said the animal, which they named Kiwa hirsuta, was so
distinct from other species that they created a new family and genus for
it.
A team of American-led divers found the animal in waters 2,300 meters
(7,540 feet) deep at a site 1,500 kilometers (900 miles) south of Easter
Island last year, according to Michel Segonzac of the French Institute for
Sea Exploration
Chelicerata include a living fossil called the
horseshoe crab
Arachnids
The whip scorpion like all chelicerates have
clawlike feeding appendages instead of mandibles (jaws) of insects
they have no anntennae
two body segments and simple eyes
Spiders have
cheicerae - piercing
mouth parts
a pair of appendages
called pedipalps used for
sensing or feeding
four pairs of walking legs
book lungs used for gas
exchange
A Centipede (Class Chilopoda) is molting its chitonous exoskeleton
one pair of legs per segment
a pair of antennae
poison claws at its anterior end
Millipede (Class Diploda)
two pairs of legs per segment
herbivorous as opposed to the carnivorous centipedes
• Flight is one key to the great success of insects.
– Flying animals can escape many predators, find
food and mates, and disperse to new habitats faster
than organisms that must crawl on the ground.
• Many insects have one or two pairs of wings
that emerge from the dorsal side of the thorax.
– Wings are extensions of the cuticle and are not true
appendages.
Fig. 33.32
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Insecta is the largest class
3 body parts with 3 pairs of
legs
two pair of wings
nitrogenous waste excreted
through Malpighian tubules
gas exchange through tracheal
tubes
mandibles (jaws)
• The internal anatomy of an insect includes
several complex organ systems.
– In the complete digestive system, there are
regionally specialized organs with discrete
functions.
– Metabolic wastes are removed from the hemolymph
by Malpighian tubules, outpockets of the digestive
tract.
– Respiration is accomplished by a branched, chitinlined tracheal system that carries O2 from the
spiracles directly to the cells.
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Butterflies undergo complete metamorphosis as
opposed to grasshopper which undergo
incomplete metamorphosis
Introduction echinoderms
• At first glance, sea stars and other echinoderms
would seem to have little in common with the
phylum Chordata, which includes the vertebrates.
• However, these animals share the deuterostome
characteristics of radial cleavage, development of
the coelom from the archenteron, and the
formation of the anus from the blastopore.
• These developmental features that define the
Deuterostomia are supported by molecular
systematics.
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Echinoderms
Coelomates
Echinoderms have water entering
into a madreporite down a water
vascular system that operates
tube feet
Deuterostomes
Radial
Symmetry
They are
capable of
everting their
stomach
through their
mouth - either
dumping the
contents or
digesting
something
outside of its
body
Deuterostomes
Mouth forms later
(second)
Forms ANUS
first
They are
capable of
regeneration
Class Astroidea
includes the
Sea Star
Tiny skin gills are
protected by spines
and pincer like
pedicillariae
Class
Ophiuroidea
includes the
Brittle Stars
Class
Echinoidea
include the Sea
Urchin and Sand
Dollar
Class Crinoidea
Sea Lillies most
primitive of the
living classes
has changed
little over time
Class Holothoroidea
sea cucumbers
lack spines
hard endoskeleton is reduced