Kingdom Animalia: Invertebrates

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Kingdom Animalia Invertebrates

• Most animals are aquatic and most are
  invertebrates. There are about 35 phyla (this
  number depends on the systematic system that is
  used).

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Phyla Calcarea and Silicea formally Phylum
Porifera

• Sessile, mostly marine organisms that
• lack symmetry and tissues ranging in height from
  1 cm to 2 m.
• About 5,500 species (_at_ 100 freshwater)
• Most are hermaphrodites also reproduce asexually
  by fragmentation.
• Planulae larvae motile and capable of dispersal.

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• Like a sac with pores with a cavity (spongocoel)
  with a large upper opening (osculum).
• Cells
• Choanocytes AKA collar cells flagellated cells
  create a current for filter feeding (AKA
  suspension feeding) and then the choanocytes trap
  food particles (which are ingested by
  phagocytosis)
• Wondering cells (amoebocytes) function in
  feeding, transport, and structure. These cells
  move through the mesohyl
• Spicules form a CaCO3 or silica skeleton.

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Planula larva
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Phylum Cnideria

• Nearly all marine more than extant 10,000
  species
• Radial symmetry, and tissues but no organs,
  diploblastic
• The ectodermis is the outer layer, and the
  gastrodermis is the inner layer, while the
  mesoglea is the substance that is located between
  the two layers.
• Carnivores with possess specialized, stinging
  cells (cnidocytes). These cnidocytes are unique
  to the phylum and contain nematocysts (like
  little harpoons) to catch food and for defense.
• Simple muscles and nerves but no brain. Instead
  they have a noncentralized nerve net (thus they
  can detect and respond to stimuli from all
  directions)

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• Basic body plan is a sac with a single body
  opening (functioning as both mouth and anus) for
  a single gastrovascular cavity which functions in
  obtaining nutrients as well as functioning as a
  hydrostatic skeleton.

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Two body plans (some species have only 1, others
have both)1. polyps are cylindrical and
sessile. 2. medusa are floating, flattened
polyps (mouth down).
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• Four classes of Phylum Cnideria

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Class Hydrozoa contains species such as Hydra,
and Obelia. Most species alternate between polyp
and medusa forms but Hydra exists only as a
polyp.
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The man-of-war's body consists of a gas-filled
(mostly nitrogen), bladder-like float (a polyp,
the pneumatophore) - a translucent structure
tinted pink, blue, or violet - which may be 3 to
12 inches (9 to 30 centimeters) long and may
extend as much as 6 inches (15 centimeters) above
the water. Beneath the float are clusters of
polyps, from which hang tentacles of up to 165
feet (about 50 meters) in length. These pelagic
colonial hydroids or hydrozoans are infamous for
their very painful, powerful sting and are very
common in Hawaiian ocean waters.
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Class Scyphozoa contains the jellyfish and the
medusa form is predominate (some species have no
polyp forms)
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Class Anthozoa contains the sea anemones and
corals. The members of this class exist in the
polyp form only. It is the largest class of the
cniderians.
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Class Cubozoa are the box jellies, they were
recently included in the Scyphozoa. Some can be
fatal to humans

• Box Jellyfish are pale blue and transparent and
  bell or cubed shaped with four distinct sides,
  therefore the name box jellyfish. You have
  virtually no chance of surviving the venomous
  sting, unless treated immediately. The pain is so
  excruciating and overwhelming that you would most
  likely go into shock and drown before reaching
  the shore. So don't go swimming alone! Be sure to
  know the first aid procedures.

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Phylum Ctenophora (marine comb jellies or sea
walnuts).

• About 100 species and all are marine ranging in
  diameter from _at_ one to ten cm.
• Similar in structure to medusae but are more
  complex (structurally) than cniderians
• The largest animals to use cilia for locomotion.
• Have colloblasts for food capture that are
  located on their two tentacles.

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Phylum Platyhelminthes

• About 20,000 species in marine, freshwater, and
  damp soil.
• Many are parasitic.
• Range in size from nearly microscopic to gt 20 m
  long
• Bilateral symmetry, acoelomates that are
  triploblastic.
• Flattened dorsoventrally from top to bottom and
• Lack circulatory systems thus diffusion is
  important
• Primitive excretory system (flame cells).
• Moderate cephalization (some have definite heads)
  and a primitive nervous system
• They form the three germ layers have only one gut
  opening,
• Many are hermaphrodites

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The three major classes of Flatworms

• Class Turbellaria - mostly free-living, marine,
  and carnivorous species. These flatworms move by
  cilia on land and use muscles for swimming. An
  example is Dugesia.
• Classes Trematoda and Monogenea (flukes) -
  parasitic flatworms that possess tough coverings.
  Trematodes have complex life cycles with
  multiple hosts e.g., blood flukes and liver
  flukes. The monogeneans are external parasites.
• 3. Class Cestoda (tapeworms) - parasitic with a
  scolex with suckers and hooks that have no
  digestive system (food is digested by the host)
  but have proglottids (reproductive sacs with
  eggs). Beef and pork tapeworms (Taenia) infest
  humans. Large tapeworms can be 20 m in length.

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Liver fluke and blood fluke
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Pork tapeworm
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Phylum Nemertea (ribbon or proboscis worms)

• There are about 900 mostly marine species (but a
  few are terrestrial)
• They are structurally acoelomatic but have a
  small fluid-filled sac (used to extend the
  proboscis) that some zoologists view as a true
  coelom.
• Range in size from less than 1 mm to over 30 m.
• Excretory, sensory, and nervous systems similar
  to those found in the flatworms but they have
  evolved a simple closed circulatory system (with
  no heart, blood moved by muscle action) and a
  complete digestive system (having both a mouth
  and an anus, instead of only one opening). They
  are the simplest animals with a complete
  digestive system.

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Phylum Rotifera (rotifers or wheel animals)

• About 1,800 species that live in fresh water
  (mostly), marine environments, or damp soil.
• Small (0.05-2.0 mm) pseudocoelomates with
  complete digestive systems and organs (lying
  within the pseudocoelom).
• Have a hydrostatic skeleton (fluid in the
  pseudocoelom).
• Some are parthenogenetic (with females only
  reproducing asexually) while others are reproduce
  sexually producing degenerate males who survive
  long enough to produce sperm when resistant
  zygotes are needed (adverse conditions).

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• Phyla Ectoprocta (tiny colonial animals
  resembling mosses about 4,500 species), and
  Brachiopoda (lamp shells which resemble bivalves
  about 330 extant species but once there were over
  30,000). The lophophorate animals all have a
  lophophore a horseshoe-shaped or circular fold
  of the body wall bearing ciliated tentacles
  surrounding the mouth for suspension feeding.

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Phylum Mollusca

• More than 93,000 species (mostly marine, but
  freshwater and terrestrial species do occur).
  Most are soft-bodied, but covered by a hard shell
  of CaCO3. Slugs, squids, and octopuses have
  reduced shells or none at all.
• They are coelomates and protostomes
• Most have separate sexes, others are
  hermaphroditic.
• There is a ciliated larval form, the trochophore,
  which is also found in marine annelids, but
  unlike the annelids, the mollusks lack
  segmentation.

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• All mollusks have a similar body plan with a
  visceral mass that contains internal organs, a
  mantle (a heavy fold of tissue that drapes over
  the visceral mass a water-filled chamber
  associated with the mantle (mantle cavity)
  housing the gills, anus, and excretory pores.
  Many species posses a rasping organ, the radula,
  for scraping food.
• All have a muscular system for movement.
• Mollusks have efficient excretory systems
  (nepridia are present)

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• Classes
• (four of eight).

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Class Polyplacophora the chitons are oval-shaped
with eight overlapping plates, marine, shelled
animals using their muscular foot (like snails)
and graze using their radulas to scrape algae
from the surface of the rocks.
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• Class Gastropoda the snails and slugs inhabit
  fresh water, marine and terrestrial environments.
  This class contains more than 40,000 species.
  Torsion, whereby one side of the visceral mass
  grows faster than the other causing the visceral
  mass to rotate up to 180 degrees and placing the
  anus and mantle cavity above the head, is unique
  to this class. Most of the gastropods have a
  single, spiraled shell for protection

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• Class Bivalvia clams, oysters, mussels, and
  scallops that have shells divided into two halves
  and that are hinged at the mid-dorsal line.
  Their gills are used for gas exchange and for
  feeding. These mollusks do not possess a radula
  nor a distinct head.

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• Class Cephalopoda octopuses, squids,
  nautiluses are all marine animals. These
  mollusks have large heads and are built for
  speed. They are the most intelligent and largest
  of the invertebrates. They are carnivores and
  possess toxins. The shell is reduced or internal
  except in the nautilus. They have a nervous
  system, sense organs, and a closed circulatory
  system.

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• http//video.google.com/videoplay?docid-201675803
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Phylum Annelida (meaning little rings) the
segmented worms

• There are about 16,500 species of marine,
  freshwater and terrestrial (moist) species that
  range in size from 1 mm to 3 m (the Australian
  earthworm).
• They possess an excretory system with
  metanephridia.
• They are hermaphroditic but do not self fertilize
  and some can reproduce asexually by fragmentation.

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• They possess chaetae (bristles) and septa that
  separate the coelom, but the digestive tract, the
  longitudinal blood vessels, and nerve cords are
  continuous along the bodys length.
• The digestive system consists of specialized
  regions. There is some cephalization.
• These worms have a closed circulatory system
  brainlike cerebral ganglia.

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• Classes
• Of
• Annelids

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Class Oligochaeta earthworms and some aquatic
species
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Class Polychaeta polychaete worms possess
parapodia almost feet for locomotion and in
some the parapodia also function in respiration
(mostly marine).
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Class Hirudinea leeches (most freshwater).
These annelids are mostly parasitic but some are
carnivorous. They secrete an anesthetic and an
anticoagulant (hirudin). Some leeches feed
infrequently but are capable of ingesting 10 xs
their weight in blood in one meal.
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Phylum Nematoda (roundworms)

• Among the most widespread of all animals _at_25,000
  known species that inhabit aquatic environments
  as well as wet soil and hosts (thus parasitic, in
  fact humans host at least 50 species).
• Usually reproduce sexually with separate sexes.
  The females are larger and there is internal
  fertilization.
• The parasitic species include pinworms,
  hookworms, Trichinella Ascaris. There are also
  species of round worms that are important
  agricultural pests.

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• Cylindrical, unsegmented, pseudocoelomates with
  tapered ends a tough cuticle that range in size
  from lt 1 mm to gt 1 m.
• Complete digestive tract and the fluid in the
  pseudocoelom serves as a blood vascular system
  for nutrient transport

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This surprise finding was surgically removed from
a 10-year-old who had come in with severe
abdominal pain and vomitting. Remarkably, he had
been feeling entirely well untill 2 days prior to
presentation. With this massive ball of ascaris
worms removed from his stomach, he is already
feeling much better.
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Phylum Arthropoda

• One million described species and many more
  probably exist. This is the most successful
  phylum of animals (both in diversity and
  numbers). They are ubiquitous.

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• General characteristics
• segmentation with fusion of some segments.
• rigid exoskeleton made of protein chitin for
  protection attachment. Molting is necessary
  for growth.
• jointed appendages that are specialized for
  movement, sensing, feeding, and reproduction.
• good sense organs (e.g., compound eyes in some,
  olfactory organs of smell, and antennae for
  tactile and olfactory senses, and cephalization
  is present
• the systems for gas exchange include gills and
  trachea
• open circulatory system
• molting

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• Arthropod Diversity

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Subphylum Trilobitomorpha the extinct trilobites
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• Subphylum Cheliceriformes (spiders, scorpions,
  mites, ticks and daddy longlegs). These
  organisms possess two body segments a
  cephalothorax and an abdomen. They also have
  chelicerae (fangs), pedipalps (in males
  copulatory organs), and spiders have book lungs
  for gas exchange.

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Class Arachnida spiders, scorpions (many are
poisonous). These animals have six pairs of
appendages on the cephalothorax as well as have
four pairs of walking legs. The extinct
eurpterids were scorpion-like marine animals that
were 3 m long and predatory.
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Class Merostomata horseshoe crabs (ancient,
marine species)
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Class Pycnogonida sea spiders, marine
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• Subphylum Myriapoda

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Class Diplopoda millipedes These are wormlike
creatures with two pairs of legs per segment.
They are detritivores.
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Class Chilopoda centipedes (see figure 33.31b).
These organisms have one pair of legs per
segment. They are carnivores possessing poison
claws for prey acquisition and for defense
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Subphylum Hexapoda. There are more insects than
all other animal species combined (species and
numbers). There are 26 orders

• roaches

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The naturalist, J. B. S. Haldane, was asked by a
cleric about what he might infer about the
Creator, based on his wide ranging study of life.
Haldane supposedly replied that the creator had
"an inordinate fondness for beetles" based on the
then current count of beetle species at around
400,000.
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Subphylum Crustacea is divided into decapod (10
footed), terrestrial and freshwater, and sessile
taxa.
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Phylum Echinodermata (spiny skinned)

• Deuterostomes
• The larvae have bilateral symmetry adults are
  not quite radial.
• They do not have a head but have nerve rings
• Possess a water vascular system with hydraulic
  canals ending in tube feet (function in
  locomotion, feeding, suction, and gas exchange).
• Have external fertilization (in some cases they
  have true random mating) and they are capable of
  regeneration.
• Possess an endoskeleton that is composed of hard
  calcium rich plates located just beneath the
  delicate skin.

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• Classes
• Of
• Echinoderms

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Class Asteroidea sea stars (capable of
regeneration). These echinoderms possess five
arms containing tube feet for locomotion and for
food acquisition. They are important marine
predators. They consists of a central disc
surrounded by the five arms
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Class Ophiuroidea brittle stars, this is the
largest class in numbers of species and may be in
numbers of individuals.
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Class Echinoidea sea urchins and sand dollars do
not possess the arms found in some of the others.
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Class Crinoidea sea lilies (ancient) and feather
stars are interesting in that the mouth and anus
are located on the upper surface in an open disc
and are connected by a simple gut.
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Class Holothuroidea sea cucumbers are soft
slug-like organisms
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Class Class Concentricycloidea There are two
species of sea daisies