Transcript newinvertebrates -me

Invertebrates
What is an animal?
An animal is...
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Multicellular.
Eukaryotic.
Heterotrophic.
An organism whose cells lack cell walls.
95% of all animal species are
grouped in an informal category:
invertebrates.
• This group is defined by describing a
characteristic that its members do not have
- a backbone!
• They range in size from microscopic dust
mites to the giant squid.
When we want to compare
invertebrates, we talk about how they
are structured and how they carry out
essential functions:
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Feeding
Respiration
Circulation
Excretion
Response
Movement
and reproduction.
There are eight phyla of
invertebrates that we will be
briefly be discussing.
Or they be asymmetrical and have no equal divisions, like
Our first group of invertebrates the
SPONGES .
3. Sponges are “filter feeders ’. Water enters through pores, bringing
food in with it. Collar cells have flagella, which move to help bring
water in.
6. Sponges may reproduce either asexually by
budding..
Characteristics of Sponges
• Habitat - most found in warm, salty water
• Movement - sessile (scientists originally
thought they were plants because they
didn’t move)
• Symmetry - asymmetrical, some radial
• Method of feeding - filter feeders
• Special structures
– Pores - bring water into body
– Collar cells - move water along with flagella
– Spicules - small needlelike structures between
cells that give body structure
– Spongin - skeleton of fibrous material
• Reproduction – asexually by forming buds
– Regeneration
– Sexually by forming sperm and eggs
(hermaphrodites)
Characteristics of Cnidarians
• Latin for stinging cells
– Examples include corals, sea anemones,
jellyfish, hydras
• Habitat - most in salt water, some hydras in
fresh water
– Hydras, corals are colonial
Cnidarians have two different body types:
1. Polyp - vase-shaped and attached
2. Medusa - bell -shaped and free-swimming
Jellyfish (illustration)
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• Movement - some sessile, some freeswimming
• Symmetry - radial
• Method of feeding - Most capture food
• Special structures
– Polyp - shaped like vase (hydra)
– Medusa - bell-shaped, free swimming
(jellyfish)
– Tentacles - armlike structure around mouth
– Stinging cells with harpoon like thread and
poison, used to capture food
Hydra (coelenterates)
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• Reproduction - asexual and sexual
– Polyp • produce buds
• Or can produce eggs or sperm
– Medusa
• Form eggs and sperm, develop larvae
• Larvae grow into polyps, new medusae bud off
Flatworms and Roundworms
Tapeworm
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What is a worm?
• A worm is an invertebrate with a soft body
and bilateral symmetry.
• There are flatworms, roundworms and
worms with segments.
• Segmented worms are not part of this phyla.
Flatworms
• They belong to the phylum Platyhelminthes.
• This phylum includes planarians and
tapeworms.
Characteristics of Flatworms
• Habitat - salt water (some fresh water)
• Movement – Free-living ones such as planarians move by
secreting a mucous track and then using their
cilia to move through the mucous.
– Parasitic ones like tapeworms use hooks and
suckers to attach themselves to the intestines of
a host organism.
• Symmetry - Bilateral
• Method of Feeding
– Planarians feed on small organisms and dead
bodies; have a mouth, pharynx, and digestive
tract
– Tapeworms feed by absorbing food already
digested by the host. No mouth or digestive
system
• Special structures
– Planarians - triangular shaped head, two eye
spots
– Tapeworms - have hooks and suckers
• Grow new segments behind the head
• Reproduction
– Planarians • reproduce asexually by dividing in two
• Can regenerate
• Can produce eggs or sperm and can exchange sperm
with one another, then lay eggs
– Tapeworms
• Each body segment makes eggs and sperm, fertilizes
itself, breaks off; eggs hatch in another host
Characteristics of Roundworms
• Belong to phylum Nematoda
• 500,000 species, including heartworm
• Habitat - soil, animals, plants, fresh and salt
water
• Movement - Muscles contract against fluid
• Symmetry - bilateral
• Method of Feeding
– Digestive system with mouth and anus
• Special structures
– Body is tube within a tube, with fluid in
between
– Three well developed tissue layers
• Reproduction
– Male and female worms reproduce sexually
Harmful Roundworms
• Hookworms - acquired by walking barefoot
over dirt; eventually move to intestines
• Ascaris - acquired by eating contaminated
food or water; eventually move to intestines
causing severe illness damaging lungs,
intestines and brain
• Trichinella -acquired by eating undercooked
pork that has been contaminated, eventually
causing fever, vomiting, pain and stiffness
• Heartworm - harmful to dogs; acquired by
dog through bite of infected mosquito,
move to heart and damage heart
Characteristics of Mollusks
• Mollusks are soft bodied invertebrates that
usually have shells.
• There are three classes of mollusks gastropods, bivalves and cephalopods.
• Habitat - land, fresh water or salt water
• Movement – Slugs and snails contract their foot muscles and
slide along a layer of mucus they have secreted
– Mussels and oysters cement themselves to a
surface
– Scallops close shells quickly to move
– Octopus and squid move by jet propulsion
• Symmetry - bilateral
• Method of Feeding
– Snails, slugs conches and other gastropods
obtain food by scraping and tearing
– Clams are filter feeders
– Octopus and squid kill and eat other animals
• Special structures
– -Mantle - a thin layer of tissue that secretes the
shell or protects the body
– Gills - organs that exchange oxygen and carbon
dioxide with the water
– Visceral mass - area of mollusk that contains
body organs
– Muscular foot - used for movement
– Open circulatory system - blood bathes organs
rather than being contained in veins and arteries
• Reproduction - most have separate sexes
– A male octopus uses one of its tentacles to
transfer sperm from its mantle cavity to the
mantle cavity of the female. Then the female
lays fertilized eggs and guards them until they
hatch
Gastropods
• Largest class of mollusks
• Includes snails, slugs, abalones, whelks, sea
slugs and conches
• Also called univalves
• Except for slugs, have single shell, pair of
tentacles and eyes at the tips
• Have radula, a tongue-like organ with rows
of teeth used to scrape
Slug
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Snail anatomy
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Bivalves
• Have two-part shell joined by a hinge
• Include clams, oyster and scallops
• Use a muscle to open and close shell
Clam
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Cephalopod
• Also called head-footed
• Include squid, octopus and chambered
nautilus
• Large developed head with foot divided into
many tentacles (8 in octopus, 10 in squid,
94 in nautilus) with suckers for capturing
prey
• Well-developed nervous system,and
enlarged eyes
• Also have closed circulatory system
• All live in oceans
• Bodies are adapted for swimming
• Some think the coloration of octopuses is a
form of communication
Nautilus (mollusk)
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Squid
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Octopus
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Characteristics of Annelids
(Segmented Worms)
• Habitat - fresh water, salt water and moist
soil
• Movement - Use bristle-like structures
called setae on the outside of each segment
• Symmetry - bilateral
• Method of feeding
– Earthworms eat soil. Soil passes through
digestive system including crop, gizzard and
intestine. Undigested soil and waste leave
worm through anus.
• Special structures – Earthworms
• have blood vessels and five hearts with a closed
circulatory system
• have nerves that respond to light, temperature and
moisture
• have a small brain
• exchange oxygen and carbon dioxide through skin
Worm
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• Leeches
– Have no setae
– Have two suckers which are used to attach to
an animal
– Feed on blood of ducks, fish and humans; suck
out two to ten times its weight in blood
– Produce an anesthetic
• Leeches
– Prior to 1900s doctors used leeches to drain
blood from sick people
– Today leeches are used to keep blood flowing to
reattached body parts.
– Leech saliva contains anticlotting chemical that
may be used with heart patients
• Marine worms
– Include species that float, burrow, build
structures, walk on the bottom or produce their
own light
– Have setae that occur in bundles
– Have fleshy outgrowths on their segments
called parapodia which help in feeding and
movement
• Scientists infer that mollusks and segmented
worms share a common ancestor because
– both have bodies with space for organs
– both have a similar larva stage
• Reproduction
– hermaphrodites
– must reproduce with another worm
Characteristics of Arthropods
• This is the largest phylum of animals. This
phylum includes insects, shrimps, spiders and
centipedes.
• Name means jointed foot, which describes the
jointed appendages (structures that grow from
the body)
• Bodies are segmented; this suggested a
common ancestor with segmented worms
• Three body parts - head, thorax and abdomen
• Also have body cavity, digestive system
with mouth and anus, nervous system,
larger brain than annelids
• Also have exoskeleton
– External covering that supports, covers and
protects the body
– Made of protein and chitin
– Is shed and replace by molting
• Arthropod is vulnerable during this time
Insects
• 700000 classified species
• Body plan
– Head - includes pair of antennae, eyes and
mouth
• Simple eyes detect light and dark
• Compound eyes can detect colors and movement
• Antennae use touch and smell
– Thorax - 3 pairs of jointed legs and possibly 1 2 pairs of wings
– Abdomen - 11 segments and no wings or legs
Butterflyanatomy
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Grasshopper
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• Open circulatory system
• Blood does not carry oxygen
• Spiracles , openings on abdomen and thorax
bring in air and give out waste gas
• Reproduce sexually; females lay thousands
of eggs
• Go through series of changes called
metamorphosis
– Complete -four stages
• Egg, larva, pupa and adult
– Incomplete -three stages
• Egg, nymph and adult
• Short life span
• Small size allows them to live in a wide
range of environments
Butterflylife cycle
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Other arthropods
• Arachnids - spider
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Two body regions
Four pairs of legs
No antennae
Have poison glands, stingers or fangs to kill
prey
– Appendages near mouth hold food
• Centipedes and millipedes
– Long bodies, many segments
• Crustaceans
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One or two antennae
Jaws called mandibles used for crushing food
Most live in water
Five pairs of legs
• First pair are claws
– Appendages on the abdomen are called
swimmerets
• Help with movement and reproduction
– Can regenerate lost parts
Crayfish
Copyright (c) TomMcHugh, Photo Researchers
Characteristics of Echinoderms
• Spiny-skinned invertebrates that live on the
ocean bottom
• Feed on dead organisms and help recycle
materials
• Most have radial symmetry
• Move by means of a water-vascular system
– Network of water-filled canals
– Thousands of tube feed connected
– Tube feet act like suction cups
• Feed by using tube feet to open the shells of
mollusks
• Importance
– Invertebrate group closely resembles the
chordates
– Viewed as advanced because the embryo
develops the same way that the embryos of
chordates do
There are several classes of
echinoderms
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Sea stars
Brittle stars
Sea urchins and sand dollars
Sea cucumbers
Starfish(illustration)
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• Sea stars
– Five or more arms
– To feed - opens shell with feet, turns its
stomach inside out, surrounds the soft body of
the mollusk
– Reproduce sexually
– Can regenerate
Starfishregeneration
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Brittle star (illustration)
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Sea urchin
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• Brittle stars
– Move quickly and break off arms as a defense
– Can quickly regenerate
• Sea urchins and sand dollars
– Have skeletons made of calcium carbonate plates
– Covered with spines
• Sea cucumbers
– Soft bodied with leathery covering
– Tentacles around mouth
– When threatened may expel internal organs