ARTHROPODS ARE ALL AROUND US!

CLASSIFICATION OF LIFE

KINGDOM ANIMALIA ⇓ PHYLUM ARTHROPODA

KEY CHARACTERISTICS Chitinous exoskeleton Segmented bodies Jointed appendages Bilateral symmetry Pair of compound eyes Brain in dorsal part of head Ventral nerve cord Open circulatory system powered by a single heart

EXOSKELETON Made up of carbohydrates (chitin) Excellent for protection Some Crustaceans add CaCO3 Excellent for protection Waterproof Efficient movement Does not grow with the animal Restricts movement

APPENDAGES Antennae Claws Walking legs Wings Flippers Other specialized features

NERVOUS SYSTEM Well-developed Brain that consists of a pair of ganglia in the head. Compound eyes Sense organs >statocysts (help maintain balance) >chemical receptors

CIRCULATORY SYSTEM Open circulation Heart long and narrow and stretches along the abdomen When heart contracts, it pumps blood through arteries that branch into smaller vessels and enter the tissues. From the tissues, blood leaves the vessels and moves through spaces in the tissues called sinuses. Eventually, blood collects in a large cavity surrounding the heart, from which it re-enters the heart through small openings and is pumped around again.

RESPIRATORY SYSTEM takes place through the body surface, and/or by means of gills, tracheae, or book lungs. -some completely lack specialized respiratory organs

REPRODUCTIVE SYSTEM Dioecious (separate gonads in males and females) Fertilization is internal in terrestrial forms; can be external in some aquatic Most lay eggs -development often proceeds with some form of metamorphosis - Parthogenesis in some (eggs hatch without being previously fertilized)

FEEDING Herbivore Carnivore Parasite Filter feeder Detritus feeder

DIGESTIVE/EXRETORY SYSTEM Undigested food becomes solid waste and leaves through anus Dispose of N-containing waste by Malpighian tubules (bathed in blood inside body sinuses) -remove waste from blood, concentrate them, and then excrete via anus Complete gut

ARTHROPODA & SUBPHYLA

4 MAJOR SUBPHYLA Class Trilobita (extinct) Class Crustacea Class Uniramia Class Chelicerata (Cheliceramorpha)

SUBPHYLUM TRILOBITA Extinct 245 million years ago First appeared 540 million years ago Closest living relative is the horseshoe crab First animals with colour vision Detritus feeders off ocean floor Some were predatory

TRILOBITA Triarthrus Lichas Paradoxides

SUBPHYLUM CRUSTACEA Include brine shrimp, crabs, water fleas, lobsters, barnacles and their relatives, etc. Primarily marine (salt water) Very diverse group Not very successful on land

CRUSTACEANS Not very successful on land: -lack of a waxy, water-tight cuticle -gills for respiration -larval stage

CRUSTACEANS Hard exoskeleton Two pairs of antennae Mandibles

CRUSTACEANS Gills -look like a row of feathers just under the exoskeleton -formed from part of the same appendages that form mouthparts and legs -movement of mouth parts and other appendages keeps a steady stream of water moving over the gills.

CRUSTACEANS Hairy hermit crab

CRUSTACEANS King Crab Dungeness Crab

CRUSTACEANS Coonstripe/dock shrimp

CRUSTACEANS Japanese spider crab spans up to 4 m (13 ft.). It is the largest arthropod

SUBPHYLUM UNIRAMIA Largest group Includes insects, millipedes, centipedes, and their relatives One pair of antennae and appendages that do not branch (uniramous appendages)

From spiracles, have long branching tracheal tubes that reach deep into the animals’ tissue. Network of tracheal tubes supplies oxygen by diffusion to all body tissues. Work well in small animals

UNIRAMIA - CLASS DIPLOPODA: MILLIPEDES Harpaphe haydeniana Octoglena anura Californiulus euphanus Characterized by long, wormlike body composed of many leg-bearing segments – are mainly detritivores

UNIRAMIA - CLASS CHILOPODA: CENTIPEDES Scutigera coleoptrata “house centipede” Scolopendra Lithobius forficatus Characterized by long, wormlike body composed of many leg-bearing segments – are mainly predators

UNIRAMIA - CLASS INSECTA CHARACTERIZED BY: three part body: -head, thorax and abdomen -has three pairs of legs attached to the thorax. INSECT COMMUNICATION: Use sound, visual, chemical (pheromones) and other types of signals.

UNIRAMIA SUBPHYLUM CHELICERATA includes arachnids, horseshoe crabs, ticks and numerous other animals which have become extinct ever since the Paleozoic era second most prominent class predators, parasites, or decomposers do not care for their young producing large numbers of offspring

CHELICERATA Live on land (except horseshoe crab) Lack antennae Presence of chelicerae (mouth parts modified to grasp food or to poison prey with venom) Most have pedipalps (2nd pair of appendages near mouth) 2 body segments Six appendages Other features: book lungs, telson, spinnerets, stingers

Horse shoe crabs: -book gills Spiders and relatives: -book lungs -contained inside a sac within the body -opening (spiracle) connects sac containing book lungs with fresh air outside. -both of these structures several sheets of tissue are layered like pages in a book. >increase surface area for gas exchange

CHELICERATA CLASS ARACHNIDA Smeringurus mesaensis Argiope bruennichi Dermacentor occidentalis

HOW ARTHROPODS FIT INTO THE WORLD: Direct and indirect source of food 2/3 of flowering plants depend on insects for pollination Symbiotic relationships Agriculture Medications - allantoin heals wounds (maggots produce) Chemicals Famines and illnesses