Arthropods • Malpighian Tubules: Sac-Like Organ That Extracts Wastes from the Blood and Adds Them to Feces That Move Through the Gut

• Phylum Arthropoda

• Insects, crabs, centipedes, spiders

• Segmented body

• Tough exoskeleton made of chitin

• Jointed appendages • Fewer body segments

• Highly specialized appendages for feeding, movement and other functions • Complex organ systems; some only found only in this phylum

• Tracheal tubes (respiration)

• Open circulatory system

• Excrete wastes through saclike tubules • Herbivores, carnivores, omnivores, bloodsuckers, filter feeders, detritivores, and parasites

• Mouthparts have evolved to allow them to eat anything imaginable

• Pincers or fangs to sickle- shaped jaws that can cut through the tissues of captured prey

• Tracheal tube: one of many branching, air-filled tubes that extend throughout the body

• Spiracle: small opening located along the side of the body through which air enters and leaves the body

• Book lung: organ that has layers of respiratory tissue stacked like the pages of a book: used to exchange gases

• Respire through feather-like gills (i.e. lobster and crabs)

• The horseshoe crab respires through organs: book gills

• Open circulatory system

• Well-developed heart pumps blood through arteries that branch and enter the tissues

• Blood leaves the blood vessels and moves through sinuses, or cavities

• The blood recollects in a large sinus surrounding the heart

• It reenters the heart and is again pumped throughout the body Terrestrial Arthropods • Malpighian tubules: sac-like organ that extracts wastes from the blood and adds them to feces that move through the gut

Aquatic Arthropods • Diffusion moves cellular wastes from the arthropod’s body into the surrounding water • Well-developed nervous system

• Brain

• Sophisticated sense organs, (i.e. eyes and taste receptors) • Well-developed groups of muscles that are coordinated and controlled by the nervous system

• Allows arthropods to beat their wings against the air to fly, push their legs against the ground to walk, or beat their flippers against the water to swim Terrestrial Arthropods

• Internal fertilization

• Sperm or sperm packet

Aquatic Arthropods

• Internal or external fertilization Molting

• As the time for molting approaches, skin glands digest the inner part of the exoskeleton and other glands secrete a new skeleton

• The animal pulls itself out of the remains of the original skeleton…this can take several hours

• The new exoskeleton is soft and the animal is vulnerable to predators

• Classified based on the number and structure of their body segments and appendages-particularly their mouthparts

• Crustaceans

• Spiders and their relatives

• Insects and their relatives Crustaceans  Primarily aquatic  Common characteristics:  2 pairs of branched antennae  2 or 3 body sections  Chewing mouthparts called mandibles  Examples:  Crabs  Lobsters  Crayfish  Shrimp  Barnacles • 2 pairs of branched antennae

• 2-3 body sections

• Mandibles: chewing mouthparts

• Primarily aquatic

• Examples: Crabs, shrimps, lobsters, crayfishes, and barnacles

• Range in size from small terrestrial pill bugs to spider crabs that have masses around 20 kg • Cephalothorax: region of a crustacean formed by the fusion of the head with the thorax

• Thorax: body part of crustacean that lies just behind the head and houses most of the internal organs

• Abdomen: posterior part of an arthropod’s body

• Carapace: the part of the exoskeleton that covers the cephalothorax

• Mandible: mouthpart adapted for biting and grinding food

• Cheliped: one of the first pair of legs of decapods (five pairs of legs: crayfishes, lobsters and crabs)

• Swimmerets: flipper-like appendages used by decapods for swimming

Spiders & Relatives  Common characteristics:  Chelicerae – pair of fangs used to stab & paralyze prey with venom  Pedipalps – appendages near mouth used to grab prey  2 body sections  4 pairs of walking legs  2 main groups:  Horseshoe crabs  Oldest living arthropods (little change in 500 million years)  Arachnids:  Spiders  Mites  Ticks  Scorpions • Chelicerates

• Mouthparts: chelicerae

• 2 body sections

• 4 pairs of walking legs

• Horseshoe crabs, spiders, ticks, and scorpions • The oldest living arthropods

• First appeared more than 500 mya and have changed little since that time

• Not true crabs at all! Anatomy is closer to that of spiders

• Chelicerae, five pairs of walking legs, a long spike- like tail used for movement

• The largest group of arachnids

• Spin webs of a strong, flexible protein called silk

• Do not have jaws for chewing: must liquefy food to swallow it

• Chelicerae: pair of mouthparts in chelicerates that contain fangs and are used to stab and paralyze prey

• Pedipalps: pair of mouthparts in chelicerates that are usually modified to grab prey

• Spinneret: organ in spiders that contains silk glands

• Small arachnids that are usually parasitic

• Chelicerae and pedipalps are specialized for digging into a host’s tissues and sucking out blood or plant fluids

• Mouthparts are so strong that if you try to pull off a tick the cephalothorax may separate from the abdomen and remain in your skin • Widespread in warm areas around the world

• Have pedipalps that are enlarged into claws

• The long, segmented abdomen of a scorpion carries a venomous stinger that can kill or paralyze prey

• Chew their prey using their chelicerae Insects & Relatives  Uniramia (i.e. insects, millipedes, & centipedes)  Common characteristics:  One pair of antennae  Jaws  Examples:  Insects  3 body segments (head, thorax, abdomen)  3 pairs of legs (attached to thorax)  Extremely variable body designs  Centipedes  May have few or many legs (more than 100)  Carnivorous with a pair of venomous claws  Millipedes  May have up to 750 legs (typically 36 – 400)  Usually feed on dead & decaying material  May secrete toxic chemicals in defense • Uniramians have jaws, one pair of antennae, and unbranched appendages

• A group that contains more species than any other group of animals living today

• Wide variety of forms and lifestyles

– Centipedes – Millipedes

• Have a body divided into three parts: – Head – Thorax – Abdomen

• Three pairs of legs are attached to the thorax

• Like all arthropods, insects have a segmented body, exoskeleton, and jointed appendages • Multiple of sense organs are used to respond to stimuli

• Compound eyes

• Chemical receptors for taste and smell on their mouthparts

• Well-developed ears that hear sounds far above the human range • Three pairs of appendages that are used as mouthparts, including a pair of mandibles

• Adaptations for feeding are not restricted to their mouthparts

• Many produce saliva containing digestive enzymes that help break down food • 3 pairs of legs

• Used for walking, jumping, flying, capturing and holding prey, etc.

• The evolution of flight has allowed insects to disperse long distances and to colonize a wide variety of habitats • Incomplete metamorphosis: type of insect development characterized by a similar appearance throughout all stages of the life cycle

• Nymph: immature form that lacks functional sex organs and other adult structures

• Complete metamorphosis: type of insect development in which the larvae look and act nothing like their parents and also feed in completely different ways

• Pupa: stage of metamorphosis in which an insect changes from a larva into an adult

• Many insects are known for their negative effects

• Termites destroy wood structures, moths eat their way through wool clothing, etc.

• Despite their association with destruction and disease, insects contribute to agriculture by pollinating 1/3 of the food that you eat

• Produce commercially valuable silk, wax and honey • Communicate using sound, visual, chemical, and other types of signals

• Much of the communication involves finding a mate

• Pheromones: specific chemical messengers that affect the behavior of development of other individuals of the same species • Ants, bees, termites, and some of their relatives form complex associations called societies

• Society: a group of closely related animals of the same species that work together for the benefit of the whole group

• Caste: group of individual insects specialized to perform particular tasks, or roles Australian termites have Arthropods Mayflies live been known to build mounds  for over a year Coelomates, bilateral twenty feet high symmetry, cephalized as larvae, but only a few and at least 100  Chitinous exoskeleton hours as feet wide.  Segmented bodies adults The larva of the  Paired, jointed appendages polyphemus moth  Highly specialized appendages consumes 86,000 The for feeding, movement, & other times its birth weight praying functions in its first 56 days mantis is the only  3 major Subphyla: Spider silk is the insect that  Uniramia (i.e. insects, strongest fiber can turn millipedes, & centipedes) known to man. its head.  Crustacea (i.e. shrimp, A bee must visit lobsters, crabs, & barnacles) 4,000 flowers in  Chelicerata (i.e. spiders, ticks, order to make scorpions, & termites) one tablespoon Scorpions fluoresce of honey. green under Out of the 40,000+ species ultraviolet light. of spiders, only about 200 are dangerous to humans.