Transcript Mollusks, Worms, Arthropods, Echinoderms

Arthropods, Echinoderms
Phylum Arthropoda
• Characteristics
– Largest group of animals
– Have jointed appendages which include legs,
antennae, claws and pincers
– Have bilateral symmetry, segmented bodies,
exoskeletons, a body cavity, a digestive system
with two openings and a nervous system
– Most have separate sexes and reproduce sexually
Arthropods
• Body Segments
– Bodies of these animals are divided into segments
similar to segmented worms
– Some have many segments, others have
segments that are fused together to form body
regions
• Exoskeleton
– A hard outer covering that supports and protects
the internal body and provides places for muscle
to attach.
– Doesn’t grow as the animals does, it is shed and
replaced during a process called molting
Insects
• Have three body regions
• Head
– Has a pair of antennae, eyes and a mouth
• Thorax
– Three pairs of legs and one or two pairs of
wings if present are attached here
• Abdomen
– Where reproductive structures are found
Insects
• Have an open circulatory system that carries
digestive food to cells and removes wastes
• Insect blood doesn’t carry O2 instead air
enters and exits through openings called
spiracles found on the abdomen and thorax
• Are the only invertebrate animals that can fly
Metamorphosis
• A series of changes that an insect goes through
• Two types
– Complete
• Includes stages of egg, larva, pupa, and adult
• Ex. Butterflies, bees, flies
– Incomplete
• Includes stages of egg, nymph, adult
• The nymph form molts several times before becoming an
adult
• Ex. Grasshoppers, crickets
Insects & Food
• Feed on a number of things have different
mouth parts to obtain food
• Grasshoppers and ants have large mandibles
for chewing
• Butterflies and honey bees have siphons for
lapping up nectar
• Aphids and mosquitoes have mouth parts
that are adapted for piercing into plants or
other organisms
Insects success
• Insects are extremely successful based
these reasons
– Tough flexible, waterproof exoskeleton
– Ability to fly
– Rapid reproduction cycles
– Small sizes
• Insects have other adaptations that
allow them to be successful
ORDER LEPIDOPTERA
What is the difference between a moth (1st picture) and a
butterfly (2nd) ?
Moth antennae end in clubs, they’re bodies are
often furrier and when at rest, their wings are flat
(butterflies rest with the wings pointing up
Arachnids
• Have two body regions
– Cephalothorax and an abdomen
• Four pairs of legs and no antennae
• Many are adapted to kill prey with
poison glands, stingers, or fangs
• Some are parasites
Arachnids
• Scorpions
– Have sharp, poison filled stinger at the end of
abdomen.
– Have a well-developed appendages which they
can grab their prey.
• Spiders
– Can’t chew their food, release enzymes into prey
to digest it—then suck the predigest liquid into its
mouth.
– Have book lungs where O2 and CO2 are
exchanged.
Brown recluse bites
cause necrosis
(death of tissue).
Arachnids
• Mites & Ticks
– Most are parasites
– Ticks have specialized mouthparts to
remove blood from the host.
– Ticks often carry disease such as Lyme
disease.
Centipedes & Millipedes
• Have long bodies and many segments,
exoskeleton, jointed legs, antennae and
simple eyes.
• Found in damp environments
• Reproduce sexually
• Make nests for eggs and stay with them until
they hatch.
• Centipedes are predators
• Millipedes feed on decaying plant matter.
Crustaceans
• Have one or two pair of antennae and
mandibles, which are used for crushing
food.
• Most live in water, but some live in
moist environments on land—such as
pill bug.
• Have five pair of legs, first pair of legs
are claws for catching and holding food.
Crustaceans
• Swimmerets are appendages on the
abdomen which help in movement and
are used in reproduction; also force
water over the gills used in O2 and CO2
exchange
• If a crustacean loses an appendage it
can regenerate it
• Include crabs, crawfish, shrimp, lobster,
and sowbugs (rolypolys)
Value of Arthropods
• A source of food
• Agriculture would be impossible without
bees and other insects to pollinate
crops
• Useful chemicals are obtain from some
arthropods
• Important part of ecological community
Controlling Insects
• Not all arthropods are of value some
are pests that carry disease or can
damage crops
Controlling Insects
• Common ways to control insects
– Insecticides, but these also kill non-harmful
insects
– Biological controls
• Types of bacteria, fungi, and viruses can be
used to control insects
• Natural predators being released to kill the
harmful insect
• Some how interfere with reproduction of the
particular insect
Origin of Arthropods
• Some fossils are more than 500 million years
old
• Scientist hypothesized that arthropods
probably evolved from an ancestor of
segmented worms because they have body
segments
• The hard exoskeleton and walking legs
allowed arthropods to be among the first
animals to live successfully on land
Phylum Enchinodermata
• Characteristics
– Have an endoskeleton covered by a thin, bumpy
or spiny epidermis
– Radial symmetrical—allowing them to sense food,
predators and other things in the environment
from all directions
– Have mouth, stomach, intestines
– Feed on a variety of plants and animals
– Have no head or brain, but have a nerve ring that
surrounds the mouth
– Also have cells that respond to light and touch
Water-Vascular System
• A characteristic unique to echinoderms
• Allows them to move, exchange CO2 and O2,
capture food, and release wastes
• It is a network of water-filled canals with
thousands of tube feet connected to it.
• Tube feet—hollow, thin walled tubes that
ends in a suction cup.
– As pressure in the tube feet changes the animal is
able to move along by pushing out and pulling in
its tube feet
Types of Echinoderms
• Sea Stars
– Echinoderms with at least 5 arms arranged
around a central point
– Uses tube feet to open shells of prey, once
open pushes its stomach into shell and
uses an enzyme to digest it
– Reproduce sexually
– Can repair themselves by regeneration
Types of Echinoderms
• Brittle Stars
– Have fragile, slender, branched arms that
break off easily
– This adaptation allows them to survive
– They can regenerate broken off body parts
– Use flexible arms for movement and tube
feet to get food into their mouths
Types of Echinoderms
• Sea Urchins & Sand Dollars
– Disk or globe-shaped animals covered in
spines
– Spines help in movement and in burrowing
– Also can protect them from predators
– Sea Urchins have five tooth like structures
around their mouth
Types of Echinoderms
• Sea Cucumber
– Soft bodied echinoderms
– Have a leathery covering
– Have tentacles around their mouth and
rows of tube feet on their upper and lower
surfaces
– When threatened, they may expel their
internal organs which will then be
regenerated in a few weeks
Value of Echinoderms
• Feed on dead organisms in the marine
environment
• Help recycle material
• Used for food
• Possible sources of medicine
• Sea stars can help control the
population of other organisms
Origin of Echinoderms
• Date back more than 400 million years ago
• Earliest echinoderms had bilateral symmetry
as adults
• Scientists hypothesize that echinoderms more
closely resemble animals with backbones than
any other group of invertebrates
– Have similar embryos that develop similar to
vertebrates
– Complex body systems