Animals, Part I Invertebrates

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Animals, Part IInvertebrates

• Introduction to Animals (Chapter 34)
• Sponges and Jellyfish (Chapter 35)
• Simple Worms (Chapter 36)
• Mollusks and Annelids (Chapter 37)
• Arthropods (except Insects) (Chapter 38)
• Insects (Chapter 39)
• Echinoderms (Chapter 40)

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Animal Features

• Animals are
• Eukaryotic
• Their cells have proper nuclei, but no cell walls
• Multicellular
• Most animals have differentiated, specialized
  tissues.
• Heterotrophic
• They must get nutrition from other organisms
• Most are herbivores (eat plants) or carnivores
  (eat meat)
• But a few are parasites (consume living hosts) or
  symbiotic (live in mutually beneficial
  relationship)

In addition, most animals are mobile (they can
move around, at least during some part of their
life) and very responsive (most have a nervous
system). Animals range in size from tiny (about a
millimetre) to huge (a blue whale is over 30m
long)
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Kingdom Animalia

• Part 1. The invertebrate animals

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The Lower Invertebrates

• Phylum Porifera, the Sponges
• Phylum Cnidaria, the Jellyfish and corals
• Phylum Ctenophora, the comb jellies
• Phylum Platyhelminthes, the flat-worms
• Phylum Rotifera, the rotifers
• Phylum Nematoda, the round-worms

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Evolution of Invertebrates
Protists
Echinoderms
Sponges
Jellyfish
Annelids and Arthropods
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144
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290
363
409
439
510
543

Paleozoic Paleozoic Paleozoic Paleozoic Paleozoic Paleozoic Mesozoic Mesozoic Mesozoic Cenozoic Cenozoic
Jurassic
Ordovician
Devonian
Carboniferous
Triassic
Ternary
Cambrian
Permian
Cretaceous
Silurian
Quaternary
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Sponges

• Sponges look plant-like, but they are in fact
  animals.
• Adult sponges are sessile, that is, they attach
  to rocks and dont move around.

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• Sponges feed by filtering food out of the sea
  water.

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Jellyfish and Relatives

• Phylum Cnidaria
• Phylum Ctenophora

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Jellyfish, Hydra and Coral (Phylum Cnidaria)

• Cnidaria can have two basic body shapes, the
  polyp shape and the medusa shape
• The two shapes are similar, with tentacles, a
  mouth opening, an epidermis and a jelly-like
  mesoglea.
• In the polyp shape, the tentacles open upwards,
• In the medusa shape the tentacles hang
  downwards.

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• Jellyfish are medusa, hydra, coral sea anemone
  are polyp

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Nematocysts (ouch!)

• Jellyfish have stinging cells called nematocysts
  on their tentacles. These can kill or paralyze
  small prey, allowing the slow-moving jellyfish to
  consume them.
• The Portuguese-man-of-war is a colonial relative
  of the jellyfish. It can be quite deadly

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Comb Jellies (Phylum Ctenophora)

• A more distant relative of the jellyfish is the
  elusive comb jelly.
• Comb jellies lack stinging cells.
• Some display bioluminescence the ability to
  glow in the dark

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Flatworms, Rotifers and Roundworms

• Phylum Platyhelminthes
• Phylum Rotifera
• Phylum Nematoda

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PlatyhelminthesThe Flat Worms

• Flatworms include harmless free-living organisms
  like the planarian
• There are also parasitic flatworms, like
  tapeworms (cestodes) and flukes (trematodes)

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Rotifers

• Rotifers are microscopic and near-microscopic
  animals. They may be spherical or worm-like

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NematodesThe Roundworms

• Nematodes are cylindrical worms, usually pointed
  at each end.
• They range in size from microscopic to about a
  meter long.
• They include both free-living and parasitic
  varieties, with the parasitic ones being larger.

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A microscopic roundworm
Warning close your eyes if you are squeamish!
Child infested with ascaris roundworms. It is
unusual to see them on the mouth nose. Usually
they come out the other end!
Ascaris, a parasitic intestinal roundworm
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Roundworms Disease
Trichina worm in Muscle

• Nematodes cause several diseases
• Trichinosis a disease of the muscles and nerves
  caused by microscopic worms from uncooked meat
  (especially pork)
• Hookworms intestinal parasite (cause bleeding)
• Pinworms intestinal parasite (cause itching)
• Skin conditions (worms enter cracks in feet)
• Heartworms (common in dogs, can kill)

Pinworms are very common. It is estimated that
between 30 and 80 percent of children in North
America have been infected by pinworms at some
point.
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The Higher Invertebrate Phyla

• Phylum Mollusca, the mollusks
• Clams, oysters, snails, slugs, octopus, squid
• Phylum Annelida, the segmented worms
• Earthworms, seaworms, leeches
• Phylum Arthropoda arthropods The joint-legged
  invertebrates.
• Crustaceans, insects, arachnids
• Phylum Echinodermata, the echinoderms
• Starfish, sand-dollars, sea urchins, sea cucumbers

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Mollusks

• Phylum Molluska

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Mollusks

• There are three main types of mollusk
• Bivalves (clams, oysters, scallops etc) have two
  shells surrounding the soft mollusk inside
• Gastropods (snails, sea-snails, slugs) often have
  a spiral shell and crawl on a belly-foot
• Cephalopods (octopus, squid, cuttlefish,
  nautilus) have multiple tentacles attached to
  their head. Cuttlefish have an internal shell
  or bone and nautilus have a spiral, chambered
  shell.

Bivalve means two shells
Gastropod means belly-foot
Cephalopod means head-foot
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Mollusks- Class 1 Bivalves

• Most bivalves are filter-feeders

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Mollusks, Class 2 Gastropods
Gastropods crawl on their bellies. They scrape
up food with a tongue-like organ called a
radula. Most gastropods have two small eyes at
the end of tentacle-like stalks above their
heads Slugs lack shells, but most gastropods
have spiral shells with torsion. Sea snails
include many species, such as whelks and conchs.
snail
Eyes
Radula
slug
Sea snail
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Mollusks, class 3 Cephalopods

• Cephalopods include octopus, squid, cuttlefish
  and nautilus
• Most cephalopods are carnivorous predators with
  tentacles or arms

octopus
squid
cuttlefish
nautilus
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Cephalopods in Action
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Parts of a Squid
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Differences in cephalopods
Cephalopod type Shell type if present Tentacles (arms tentacles) Tentacle features Fun Facts
Squid None 10 (82) Suckers and hooks Colossal squid are the largest invertebrates
Octopus None 8 (80) Suckers Secrete ink to escape predators
Cuttlefish Internal cuttlebone 10 (82) No suckers The most intelligent invertebrates. Chameleons of the sea.
Nautilus Spiral chambered Up to 90 (90 0) No suckers Most of its shell is empty chambers used for buoyancy
The term tentacle is used here for all
tentacle-like limbs. In fact, the smaller limbs
of the squid are properly called arms, and only
the longer ones are tentacles.
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The Colossal Squid
Largest Invertebrate Ever?
For over 100 years, scientists had suspected that
there were some really large squid lurking in the
deep oceans. Jules Verne wrote a fictional
account of such a creature in his 1870 novel
20000 Leagues Under the Sea In 2003 a complete
specimen of a young squid was found (shown on
table above) In 2007 one weighing over 1000 lb
was captured near Antarctica (upper left)
Possible length of adult?
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Convergent Evolution
Mollusks and vertebrates have evolved separately
for nearly a billion years, so they have no close
common ancestors. Nevertheless, some features of
cephalopods are remarkably similar to features
found in some vertebrates. This is a case of
convergent or parallel evolution.
?octopus eye Cats eye?
?octopus beak Parrot beak ?
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Convergent Evolution
?cuttlefish camouflage
chameleon camouflage ?
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• 1. Define a mollusk
• 2. List the three types of mollusk, and give an
  example of each.
• 3. What is the largest known mollusk?
• 4. What is convergent evolution?
• 5. Give three examples of convergent evolution
  features that appear in mollusks, and state what
  other organism they are convergent to.

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Annelids

• Phylum Annelida

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Annelids the Segmented Worms

• Examples
• Earthworms
• Sandworms
• Leeches

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Geological Timescale (Arthropods)
Crustaceans (Shrimp, Lobsters, Crabs etc.)
? Extinct
Trilobites
? Extinct
Sea Scorpions
Annelid Ancestor (Worm)
Horseshoe Crabs
Chelicerates
Arachnids (spiders, scorpions, mites, ticks)
Sea spiders
Myriapods (Millipedes Centipedes)
Uniramia
Insects
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65
144
206
245
290
363
409
439
510
543

Paleozoic Paleozoic Paleozoic Paleozoic Paleozoic Paleozoic Mesozoic Mesozoic Mesozoic Cenozoic Cenozoic
Jurassic
Ordovician
Devonian
Carboniferous
Triassic
Ternary
Cambrian
Permian
Cretaceous
Silurian
Quaternary
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Giant EarthwormThe Largest Annelid
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Facts about annelids
Thats why some people (inaccurately) say that
worms have Five hearts

• Annelids are called segmented worms because
  their bodies appear to be made of about a hundred
  similar segments stuck tightly together.
• Most annelids are hermaphrodites, they have both
  male and female sex organs, but they must still
  mate with different worms.
• Earthworms have no real heart, but they have five
  pairs of aortic arches that pump blood
• Annelids have setae that extend from their body
  like tiny legs. Earthworms are hair-like and
  retractable, but sandworms have paddle-like
  setae.

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Arthropods

• Phylum Arthropoda

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Arthropods

• Joint-legged invertebrates
• Trilobites (extinct)
• Crustaceans
• Insects
• Arachnids)
• Centipdes Millipedes
• See phylogenetic tree (p. 745)

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Arthropod Features

• All arthropods have
• An exoskeleton (external skeleton containing a
  tough carbohydrate compound called chitin)
• Jointed appendages (legs and/or claws)
• Segmented body design
• Ventral nerve cord (their main nerve goes down
  their belly side instead of their back side)

Segmented body
Tough exoskeleton
ventral nerve
Jointed legs
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• Most (but not all) arthropods also have these
  features
• Compound eyes
• Eyes containing hundreds of individual lenses
• Moulting
• As the arthropod grows is must shed its old
  exoskeleton several times.

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Arthropods, Subphylum 1 Trilobites

• Trilobites were ocean-dwelling arthropods of the
  Palaeozoic era.
• Trilobites are all extinct. They are found only
  as fossils

Artists conception of trilobite
Trilobite fossil
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Arthropods Subphylum 2 Crustaceans

• Most crustaceans are aquatic
• crabs, lobsters, crayfish, barnacles and
  shrimp.
• Two types of crustaceans are terrestrial, and are
  often mistaken for insects.
• Sow-bug, pill-bug

Sow bug pill bug
except the horseshoe crab, which is more closely
related to the arachnids
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Body Parts in a Crustacean

• The body is divided into two main regions
• The cephalothorax ( a fused head thorax
  protected by a tough shell or carapace)
• The abdomen (segmented tail area)
• Most crustaceans are decapods (meaning 10 legs).
  They have four pairs of walking legs and one pair
  of claws (chelipeds).
• In addition to their main legs, they have several
  other appendages
• Antennae and antennules
• Swimmerets
• Maxilla and maxillipeds
• A telson (tail-piece) and uropods (tail)

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Internal Anatomy of a Crustacean
The heart of a crustacean is on its dorsal (back)
side, and its largest blood vessel runs along its
back. It has a complete digestive system, with a
two-part stomach, a digestive gland and an
intestine. Its largest nerve runs along its
ventral (belly) side, from the brain to the tail,
with several nerve bundles or ganglia along
it. Respiration is through gills under the
carapace.
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Arthropods Subphylum 3 Chelicerates

• Chelicerates include
• Sea scorpions (extinct but huge)
• Horseshoe crabs
• Sea spiders
• Arachnids
• (arachnids are the only
• group we will examine in
• detail.)

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ArachnidsPhylum Arthropoda, Subphylum
Chelicerata, Class Arachnida

• Arachnids include spiders, scorpions, ticks and
  mites.
• Most arachnids have four pairs of walking legs
  (eight-legged freaks), but may also have
  additional appendages
• Scorpions have a pair of chelicerae (claws)
• Spiders scorpions have pedipalps near their
  mouth.

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Arachnid Facts
The worlds largest spider is the Goliath
bird-eater tarantula over 30 cm (one foot!)
long with 5 cm fangs.
Eriophyid mites are among the smallest of all
arthropods, measuring only 125 to 250 µm in
length
The most venomous spider in the world is the
Brazilian wandering spider
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Arthropods, Subphylum 4 Uniramia

• Uniramia include
• Myriapods (centipedes and millipedes)
• Insects (over 750 000 species of them!)

in older classification systems, Mandibulata is
sometimes used instead of Uniramia
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Myriapods centipedes millipedes
?Centipede
Millipede?
Ok, they dont really have exactly 100 or exactly
1000 legs. nuff said.
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Insects, the hexapodsPhylum Arthropoda,
Subphylum Uniramia, Class Insecta

• Insects are the most widespread of all
  invertebrates.
• Insects exist in nearly every climate, and there
  are over 750 000 species
• (thats ¾ of a million different types of
  insect!)

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Insect Features

• Insects have the features of arthropods, plus
• Three pairs of walking legs (6 legs total)
• Three distinct body divisions
• Head (front end of body)
• Thorax (chestor central region of body)
• Abdomen (back end of body)
• (In a few insects, eg. Grasshopper, the head and
  thorax are partially fused into a
  cephalothorax)
• Some insects also feature
• Metamorphosis (complete or incomplete)
• One or two pairs of wings in the adult stage.

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Metamorphosis

• Metamorphosis is a major change in body form as
  an organism matures
• Metamorphosis is found in several types of
  animal, but most notably in
• Insects
• Amphibians
• The younger life stage is usually called the
  larva, the older life stage is the adult.
• Some forms of metamorphosis have additional
  stages, such as nymph or pupa.

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Types of Metamorphosis

• Incomplete metamorphosis
• The body change is usually minor, such as the
  growing of wings or a slight change in body
  shape. Eg. Grasshopper
• When metamorphosis is incomplete, the term nymph
  is often used instead of larva.
• Complete metamorphosis
• The body change is major, and the adult appears
  completely different from the young organism.

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Incomplete metamorphosis of Grasshopper
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Complete Metamorphosis
3rd Instar Larva
Pupa
2nd Instar Larva
1st Instar Larva
Adult
Egg
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A Few of the Many Orders of Insect

• Coleoptera beetles, ladybugs
• Diptera flies, mosquitoes
• Orthoptera Grasshoppers, crickets
• Lepidoptera butterflies, moths
• Hymenoptera bees, wasps, ants

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Float like a Lepidoptera Sting like a
Hymenoptera
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Insect Systems

• Respiratory system
• Insects have no lungs. They have holes called
  spiracles on the sides of their abdomen. The
  spiracles lead air into a system of tubes called
  tracheae. Their blood does not carry oxygen (no
  hemoglobin)
• Digestive system
• Contains crop and gizzard (foregut) the stomach
  with several caeca or storage sacs (midgut) and
  the intestine with rectum and anus (hindgut)
• Excretory system
• Insects do not have kidneys as such. Instead
  they have a cluster of tubes called Malpighian
  tubules that gather liquid wastes into the
  intestine.

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spiracle
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The myth of giant insects

• If an ant were the size of a human, it could lift
  2000 pounds over its head
• Giant radioactive insects terrorize Nevada towns.
• Cockroaches could survive nuclear wars

MYTH Busted
If an ant were the size of a human It couldnt
even lift its own body weight due to the
square-cube law. Strength increases as the
square of size, but weight increases as the cube
of size
MOVIE MYTH Busted
Plausible
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The Truth

• Insects and other arthropods have very heavy
  exoskeletons. Increasing the size of an insect
  would increase its exoskeleton to the point where
  it would be difficult to lift.
• Insects also have a primitive respiratory system.
  Without proper lungs large insects have a
  difficult time getting oxygen.
• Fact Much larger (but not truly gigantic)
  insects existed in the paleozoic era (200 million
  years ago) when there was more oxygen in the
  atmosphere.

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Titaneus giganteus Palaeozoic
Dragonfly Todays largest insect 300 million
years ago (a model, not the real thing)
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Echinoderms

• Starfish and their relatives

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Phylum EchinodermataThe Echinoderms

• Echinoderms include
• Starfish
• Sea Urchins
• Sand dollars
• Sea cucumbers
• Sea lilies

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Echinoderm Features

• All Echinoderms are aquatic
• Echinoderms are deuterostomes
• This means their digestive system develops from
  both ends, no just from the mouth end.
• It also means that they are more closely related
  to vertebrates than their appearance would
  suggest.
• Echinoderms have radial symmetry.
• Rather than more common bilateral symmetry.
• Most have five lines of symmetry (pentaradial)
  but a rare few have up to two dozen.

see page 784 bottom right
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Five lines of symmetry
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Echinoderm Movement

• Echinoderms have a water vascular system that
  pumps water through canals in their bodies
• The water vascular system also operates many tiny
  tube-feet underneath the body to allow the
  echinoderm to crawl along the bottom.

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Structure of a Starfish
Digestive system in pale green Water vascular
system in pale orange Reproductive system in
purple
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Chordates

• Phylum Cordata
• The vertebrates and their relatives

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Non-vertebrate Chordates

• Phylum Chordata includes all organisms with a
  dorsal nerve chord and with a notochord at some
  stage of life.
• A notochord is a tough, flexible rod that
  protects the nerve.
• Most chordates are vertebrates, that is they
  develop a backbone around their notochord, but
• Lancelets (eg. Amphioxus) keep their notochord
  for life and never develop a true backbone.
• Tunicates (Sea squirts) lose their notochord and
  never develop a backbone

Dorsal means running along the backside, as
opposed to the belly side
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Amphioxus sp. (a lancelet)
?Diagram of a lancelet
Photograph of a lancelet?
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Tunicates (sea squirts)
A whole colony of sea squirts
?Sea squirt diagram
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End of the InvertebratesNow its time to develop
someBackbone, like the rest of the chordates