Download Arthropods and Echinoderms

Ms. Moore
2/15/13
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Phylum: Arthropoda
What is an Arthropod?
• Arthropods have a segmented body, a tough
exoskeleton, and jointed appendages
Exoskeleton: tough external covering; like a suit
of armor that supports and protects the body
Chitin: carbohydrate that makes up exoskeleton
Appendages: structures that extend from the body
wall
• Antennae or legs
 1st
arthropods appeared in
the sea more than 600 m.y.a.
 Natural
selectionfewer
body segments and highly
specialized appendages for
feeding, movement, etc.
 At
least 75,000 species have
been identified
 Feeding
• Include herbivores, carnivores, omnivores,
bloodsuckers, filter feeders, scavengers, and
parasites.
• Mouth parts range depending on diet
 Respiration of Terrestrial Arthropods
• Tracheal tubes: network of tubes that extend
throughout the body
• Spiracles: small openings along the side of the
body attached to tracheal tubes
• Book lungs: organs that have layers of
respiratory tissue stacked like the pages of a
book
 Respiration of Aquatic
• Featherlike gills
Arthropods
 Circulation
• Open circulatory system
 Excretion
• Malpighian tubules: saclike organs that extract
wastes from blood and add to feces
• Diffusion occurs in aquatic arthropods.
 Response
• Well developed nervous system, brain, ventral
nerve cord, and sense organs (compound eyes).
 Movement
• Use well-developed groups of muscles that are
coordinated and controlled by nervous system
• Flex or extend muscles
 Reproduction
• Terrestrial: internal fertilization; males have
reproductive organ or sperm packet
• Aquatic: internal or external fertilization
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Exoskeleton does not
grow with the animal.
When they outgrow their
exoskeletons, arthropods
undergo periods of
molting
Molting: arthropod sheds
its entire exoskeleton and
manufactures a larger
one to take its place;
controlled by the
endocrine system
(hormones)
 Arthropods
are classified
based on the number and
structure of their body
segments and appendages—
particularly their mouthparts.
 3 Groups:
• Crustaceans
• Spiders and relatives
• Insects and relatives
 Subphylum: Crustacea
 Primarily
aquatic
 Crustaceans
typically have two pairs of
antennae, two or three body sections, and
chewing mouthparts called mandibles.
 Cephalothorax:
formed by fusion of the
head with thorax
 Thorax: lies just behind
the head and houses
internal organs
 Abdomen: posterior
part of the body
 Carapace: part of
exoskeleton that covers
cephalothorax
 Mandible: mouthpart
adapted
for biting and grinding food
 Gills are attached to
appendages associated with
cephalothorax
 Decapods have five pairs of
legs.
 Chelipeds: first pair of legs;
bear large claws
 Swimmerets: flipper like
appendages used for swimming
 Final abdominal segment is
fused = tail.
 P. 721
drawing
 Crustaceans
include:
• Crabs
• Shrimps
• Lobsters
• Crayfishes
• Barnacles (sessile)
How are these alike and different?
 Subphylum: Chelicerata
 Chelicerates
have mouthparts called
chelicerae and two body sections, nearly all
have four pair of walking legs.
 Lack
antennae found on most arthropods.
 Cephalothorax: brain, eyes, mouth, legs
 Abdomen: internal
organs
 Chelicerates
have two pairs of
appendages attached near the mouth
• Chelicerae: contain fangs used to stab and
paralyze prey
• Pedipalps: longer than chelicerae, modified to
grab prey
 Use
book gills or book lungs
 2 classes:
• Merostomata: horseshoe crabs
• Arachnida: spiders, mites, ticks, scorpions
 Horseshoe Crabs
• among oldest living arthropods, appeared more
than 500 m.y.a.
• Heavily armored like crabs, but have anatomy
closer to spiders
 Spiders
• Largest group of arachnids
• No jaws—must liquefy food to swallow
• Chelicerae inject venom paralyze prey inject
digestive enzymes stomach breaks down
• Spinnerets: organs that contain silk glands
• P722 drawing
 Mites and Ticks
• Small arachnids
• Often parasitic
• Chelicerae and pedipalps specialized for digging
into host’s tissues and sucking out blood/plant fluids
• Cephalothorax may stay in skin if pulled out
 Scorpions
• Pedipalps enlarged into claws
• Abdomen carries a venomous stinger that can kill or
paralyze prey
• Unlike spiders, scorpions chew prey using
chelicerae
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Subphylum: Uniramia
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Uniramians have jaws, one pair of antennae, and
unbranched appendages.
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Centipedes:
• Class: Chilopoida
• Segmented; each segment = one pair of legs, up to 100 pairs
• Carnivores: mouthparts with venomous claws
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Millipedes:
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Class: Diplopoda
Highly segmented; each segment = 2 pairs of legs
Feed on dead and decaying plant material
Timid and roll into ball for protection
 What
is an Insect?
• Insects have a body divided into 3 parts—
head, thorax, and abdomen. 3 pairs of legs
are attached to thorax.
• Typical insect also has: pair of antennae, pair of
compound eyes, two pairs of wings on thorax,
and tracheal tubes.
 The
class, Insecta, contains more species
than any other groups of animals.
Living Species
Insects
Noninsect
Arthropods
Nonarthropod
Invertebrates
Vertebrates
 Use
sense organs to detect external stimuli
 Compound
eyes: made of many lenses that
detect changes in color and movement
 Chemical
receptors for taste on mouth, legs,
and antennae
 Sensory
 Ears
hairs on legs
can be found in odd places (behind legs)
 Insects
have 3 pair of appendages used
as mouthparts:
• Mandibles used to saw and grind food (ant)
• Tubelike mouthpart use to suck nectar (moth)
• Spongelike mouthpart used to lap up food (fly)
 Some
produce saliva containing
digestive enzymes to help break down
food (nectarhoney)
3
pairs of legs can be used for walking,
jumping, or capturing and holding prey.
 Flight—two
pairs of wings made of chitin
(also makes up exoskeleton)
 Colonize
a wide variety of habitats.
 Metamorphosis: process
of changing shape
and form
• Incomplete Metamorphosis: immature forms that
undergo gradual change, look very much like adults
• Nymphs: immature forms; lack functional sex organs
and other features like wings; molt several times and
grow to acquire adult structures
• Complete Metamorphosis: hatch into larvae that look
and act nothing like parents; also feed completely
different
• Pupa: stage in which an insect changes from larva to
adult; body completely remodeled inside and out
 P729
stages and 3 examples of insects in each
 Negative
effects
• Termites destroy wood structures
• Moths eat clothing and carpets
• Bees and wasps produce painful stings
 Positive
effects
• Pollination: 1/3 food we eat is pollinated by
insects
• Products: silk, wax, honey
 Visual
Cues
• Fireflies: light producing organ produces series
of flashes
 Chemical
Signals
• Pheromones: specific chemical messengers that
affect behavior or development of other
individuals
• Fx: to signal alarm or alert; mating
 Society: group
of closely related animals
of the same species that work together for
the benefit of the whole group (more than
7 million individuals)
 Castes: specialized
individuals/body form
to perform particular tasks
• Reproductive females that lay eggs called queens
• Reproductive males
• Workers
 Each
species has its own “language” of
visual, touch, sound, and chemical signals
 Bees
use a form of dance for
communication
• Round dance: food is nearby to hive
• Waggle dance: food is farther away from hive
• Also shows direction of food…
 Recap
 Give
an example of 5 different insects
and a specialized function/body part of
each.
 Echino-
means “spiny” and dermis means
“skin”
 Endoskeleton: internal skeleton formed
from hardened plates of calcium
carbonate
 Echinoderms are characterized by:
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spiny skin
an internal skeleton
a water vascular system
suction-cuplike structures called tube feet
Most adults exhibit five-part radial symmetry.
Only live in the sea
 Water
vascular system: internal tube
system; filled with fluid; carries out
respiration, circulation, and movement
 Madreporite: openings to outside from
• In sea stars, this connects to a ring canal that
forms a circle around the mouth five radial
canals extend from this point
 Tube foot: suction cup
• 100s attached to each radial canal
 Feeding
• Scrape algae from rocks
• Tube feet to capture/open prey
• Sea stars feed on mollusks open shell and
pours enzymes that partially digests mollusk
pulls in stomach and prey to mouth
 Respiration
and Circulation
• Thin-walled tissue of tube feet
• Water-vascular system
 Excretion
• Digestive waste  anus
• Nitrogenous waste  ammonia through skin and gills
 Response
• Highly developed nervous system: nerve ring and
radial nerves
• Scattered sensory cells
 Movement
• Tube feet
• Determined by endoskeleton
 Reproduction
• External fertilization
• Larvae have bilateral symmetry
 Sea
Urchins and Sand
Dollars
• Large solid plates that form a
box around internal organs
• Detritivores or grazers that eat
algae
 Brittle
Stars
• Slender, flexible arms
• Can shed arms if under attack
• Filter feeders or detritivores
 Sea
Cucumbers
• Look like moving
pickles
• Travel in herds
• Detritus feeders suck
up matter on sea floor
 Sea
Stars
• Carnivorous
• Incredible healing
powers
• Each piece grows into
new star
 Sea
Lilies and Feather Stars
• Filter feeders
• Oldest class of echinoderms
• Attached to ocean bottom or atop
coral reefs
 Marine
habitats
• Population control
• Crown-of-Thorns: feeds on coral