Arthropods, Echinoderms. Phylum Arthropoda Characteristics –Largest group of animals –Have...
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Transcript of Arthropods, Echinoderms. Phylum Arthropoda Characteristics –Largest group of animals –Have...
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
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
ORDER LEPIDOPTERA
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.
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