ArthropodaArthropoda

Jointed Legged AnimalsJointed Legged Animals

IntroductionIntroduction

More than a million artrhopods More than a million artrhopods have been identified to date.have been identified to date.

More have yet to be discoveredMore have yet to be discovered

Unbelievable diversity of animalsUnbelievable diversity of animals

SubphylaSubphyla

Subphylum ChelicerataSubphylum Chelicerata – – spiders, ticks, mites , scorpions, spiders, ticks, mites , scorpions, and horseshoe crabsand horseshoe crabs

Subphylum MandibulataSubphylum Mandibulata Class CrustaceaClass Crustacea – crabs, lobster, – crabs, lobster,

shrimpshrimp ClassClass DiplopodaDiplopoda – Millipedes – Millipedes ClassClass ChilopodaChilopoda – Centipedes – Centipedes ClassClass InsectaInsecta - Insects - Insects

Body Plan:Body Plan:

Exoskeleton made of chitinExoskeleton made of chitin Provides protectionProvides protection Waterproof – restricts water lossWaterproof – restricts water loss

Head, abdomen, thoraxHead, abdomen, thorax Some leathery – insectsSome leathery – insects Some hard – ticks, crabs, lobsterSome hard – ticks, crabs, lobster

FeedingFeeding:: Every method of feeding is represented by Every method of feeding is represented by

arthropodsarthropods Herbivores, carnivores, parasites, filter feeders Herbivores, carnivores, parasites, filter feeders

and detritus feedersand detritus feeders   Some are specific, some (locusts) eat Some are specific, some (locusts) eat

anything greenanything green Some crabs and insects eat other live Some crabs and insects eat other live

animalsanimals Some eat animals and plants already dead Some eat animals and plants already dead External parasites, internal parasitesExternal parasites, internal parasites Filter feeders – barnacles Filter feeders – barnacles

RespirationRespiration::

3 types of respiration3 types of respiration 1.1.      gillsgills 2.2.      book gills and book lungsbook gills and book lungs 3.3.      tracheal tubestracheal tubes

RespirationRespiration::

Book gills – Limulus , and book lungs Book gills – Limulus , and book lungs spiders are arranged like pages in spiders are arranged like pages in a booka book

––            more surface areamore surface area

Internal Transport:Internal Transport:

Well developed heartWell developed heart open circulatory system – some open circulatory system – some

vessels, but open into tissuesvessels, but open into tissues Blood moves into sinuses where it Blood moves into sinuses where it

collects and is returned to the collects and is returned to the heartheart

Excretion:Excretion:

Solid wastes leave through the anusSolid wastes leave through the anus Nitrogen wastes are removed in various Nitrogen wastes are removed in various

waysways These are bathed in blood inside body These are bathed in blood inside body

sinusessinuses The tubules remove wastes from the The tubules remove wastes from the

blood, concentrate it and then add it to blood, concentrate it and then add it to undigested food before it leaves the undigested food before it leaves the body body

Excretion:Excretion:

Aquatic arthropods – diffusion Aquatic arthropods – diffusion through unarmored places on the through unarmored places on the bodybody

Many aquatic arthropods (Lobster Many aquatic arthropods (Lobster for one) use a pair of “green for one) use a pair of “green glands” glands”

Response:Response: Most have well developed nervous systemsMost have well developed nervous systems all have a brain that consists of a pair of all have a brain that consists of a pair of

ganglia in the headganglia in the head Pair of nerves run around esophagus and Pair of nerves run around esophagus and

connect brain to spinal cord that runs connect brain to spinal cord that runs around ventral side of bodyaround ventral side of body

Several more ganglia, one for each body Several more ganglia, one for each body segment usually, coordinate movement of segment usually, coordinate movement of wings and legs. (That is why they can still wings and legs. (That is why they can still flap wings, or walk around after the head is flap wings, or walk around after the head is cut off) cut off)

Response:Response:

Compound eyes w/ as many as Compound eyes w/ as many as 2000 separate lenses2000 separate lenses

Can detect color and motion very Can detect color and motion very well – ever try to swat a fly?well – ever try to swat a fly?

Human eye vs. Insect eye Human eye vs. Insect eye Blades of a fan, UV lightBlades of a fan, UV light

Response:Response:

Sense and taste receptors (may be Sense and taste receptors (may be in strange places such as legs, or in strange places such as legs, or antennae)antennae)

Sensory hairs feel the movement Sensory hairs feel the movement of air or waterof air or water

May have well developed ears – May have well developed ears – eardrum in grasshopper is behind eardrum in grasshopper is behind the legs - can hear sounds the legs - can hear sounds humans can’t humans can’t

Protection:Protection:

ExoskeletonExoskeleton Can drop a claw or leg to get awayCan drop a claw or leg to get away Camouflage Camouflage

Movement:Movement:

well developed muscle systemswell developed muscle systems

generate force by contracting and generate force by contracting and transfer force to exoskeleton transfer force to exoskeleton

Reproduction:Reproduction:

Males and females produce sperm Males and females produce sperm and eggand egg

Fertilization occurs within the body Fertilization occurs within the body of the femaleof the female

Growth and Development:Growth and Development:

MoltingMolting Epidermis digests inner part of Epidermis digests inner part of

exoskeleton and absorbs much of exoskeleton and absorbs much of the chitinthe chitin

Secretes a new exoskeleton under Secretes a new exoskeleton under the old onethe old one

Growth and Development:Growth and Development:

Arthropod comes completely out of Arthropod comes completely out of its old exoskeletonits old exoskeleton

Commonly eats old exoskeleton, Commonly eats old exoskeleton, then grows then hardens – what is then grows then hardens – what is the first thing to harden in a the first thing to harden in a lobster molt? – mouthparts so it lobster molt? – mouthparts so it can eat the old exoskeleton can eat the old exoskeleton (recycle the chitin)(recycle the chitin)

  

Carcinus maenusCarcinus maenus

Cancer irroratusCancer irroratus

Callinectes sapidusCallinectes sapidus

Uca minaxUca minax

Libinia emarginataLibinia emarginata

Libinia emarginataLibinia emarginata

Subphylum Subphylum ChelicerataChelicerata

spiders, ticks, mites , spiders, ticks, mites , scorpions, and scorpions, and

horseshoe crabshorseshoe crabs

Characteristics:Characteristics:

2 part body2 part body mouthparts called cheliceraemouthparts called chelicerae lack sensory “feelers” found on lack sensory “feelers” found on

other arthropodsother arthropods

Horseshoe Crabs:Horseshoe Crabs:

Limulus polyphemusLimulus polyphemus Not true crabsNot true crabs Over 430 million years oldOver 430 million years old Living fossilsLiving fossils 5 pr walking legs5 pr walking legs spikelike tailsspikelike tails up to 60 cm longup to 60 cm long

Horseshoe Crabs:Horseshoe Crabs: