Biology - Chapter 28 “Arthropods”

Introduction to Arthropods Phylum Arthropoda - vary enormously in size, shape, and habits

Crustaceans Crustacea- over 35,000 species, mainly aquatic tiny as a water flea (0.25 mm) to Japanese spider crabs (6 meter) characterized by: a hard exoskeleton; 2 pairs of antennae; mouthparts called mandibles

Introduction to Arthropods Although there are many different types of arthropods, they all have four important arthropod features: Tough exoskeleton – shed to allow for growth (molt) Protection Prevent water loss Made up of chitin (protein) 2. Series of jointed appendages in pairs 3. Segmented body – head, thorax, abdomen

Introduction to Arthropods Well developed nervous system -- sense organs – eyes, touch, hearing brain, located in dorsal part of head open circulatory system, powered by a single heart Flows into open cavities called sinuses

Introduction to Arthropods Development through Metamorphosis: 1. Incomplete metamorphosis eggs hatch to nymph (kid) to adult examples: grasshoppers and crickets

Spiders and their Relatives also lack sensory “feelers” found on the heads of most other arthropods the two-part body is: 1. Cephalothorax 2. Abdomen

Introduction to Arthropods 2. Complete metamorphosis involves four stages: a) the egg b) larvae (a wormlike stage that does not look like the adults) c) pupa (an inactive stage that totally rearranges the body) d) the adult Moths, butterflies, flies, lady bugs

Introduction to Arthropods Phylum Arthropods is subdivided into three subphyla: 1. Subphylum Chelicerata Includes spiders, ticks, mites, scorpions, and horseshoe crabs

Spiders and their Relatives Cephalothorax- contains the brain, eyes, mouth and mouthparts, and esophagus Abdomen- contains most of the internal organs

Spiders and their Relatives All chelicerates have two pairs of appendages attached near the mouth that are adapted as mouthparts first pair are chelicerae second pair is longer, and called pedipalps both serve different feeding job

Spiders and their Relatives Among the oldest chelicerates are the horseshoe crabs

Spiders and their Relatives Scorpions- carnivores that prey on other invertebrates, usually insects pedipalps are enormously enlarged into a pair of claws abdomen is long and segmented; ends in a venomous barb to sting prey

Introduction to Arthropods 3 Subphylums 1. Subphylum Crustacea includes crabs, shrimp, crayfish

Crustaceans Main body parts are the head, thorax, and abdomen in many, the head and thorax have fused = cephalothorax, many (crabs, lobsters)

Introduction to Arthropods 3. Subphylum Uniramia includes most arthropods: centipedes, millipedes, and all insects (bees, moths, flies, grasshoppers, beetles)

Insects Anatomy Head Antennae (sensory appendages) Mouthparts Compound eye Thorax 3 pairs of legs Wings? Abdomen

Insects and their Relatives Subphylum Uniramia- more species than all other groups of animals alive today! 1. Class Insecta – flies, bees, butterflies, dragonflies, grasshoppers, lice, mosquitos 2. Class Chilopoda – centipedes 3. Class Diploda -- millipedes

Section 28-2 Spiders and their Relatives Have 4 pairs of walking legs long spike-like tails can grow up to 60 cm long, about the size and shape of a frying pan newly hatched are called trilobite larvae because they look so much like them

Section 28-2 Spiders and their Relatives Class Arachnida- includes spiders, ticks, scorpions, and mites have 4 pairs of walking legs pedipalps capture and hold prey; chelicerae adapted for biting and sucking out soft parts

Section 28-2 Spiders and their Relatives Spiders- predators that usually feed on insects capture prey in a variety of ways: ensnare in a web stalk, and then pounce ambush under camouflage, then leap out and grab

Section 28-2 Spiders and their Relatives Once captured: 1. Hollow fanglike chelicerae inject paralyzing venom 2. Mouth introduces enzymes 3. Enzymes break down tissue 4. Spider sucks up the liquefied tissues with esophagus and specialized pumping stomach

Section 28-2 Spiders and their Relatives Whether or not they spin webs, all spiders produce a strong, flexible protein called silk produced in special glands in the abdomen is 5 times stronger than steel makes webs, cocoons for eggs, or wrappings for prey

Section 28-2 Spiders and their Relatives Forces the liquid silk through organs called spinnerets it then hardens into a single strand do not have to learn “how” to spin the intricate webs; it is programmed into their brain as soon as they hatch

Section 28-2 Spiders and their Relatives Mites and Ticks- small arachnids, many of which are parasites the chelicerae are needlelike structures that are used to pierce the skin of their hosts the chelicerae also have large teeth to help the parasite hold on to the host

Section 28-2 Spiders and their Relatives Some, such as spider mites,are major agricultural pests others, such as chiggers, mange and scabies mites,cause painful itching rashes in humans tick bites are not just annoying; they may also spread Rocky Mountain spotted fever and Lyme disease

Section 28-2 Spiders and their Relatives Scorpion grabs the prey with it’s pedipalps; then whips the abdomen over it’s head to sting the prey- thus killing or paralyzing it they like to crawl in moist, dark places- good idea to check your shoes when putting them on!

Discuss the distinguishing characteristics of crustaceans. Section 28-3 Crustaceans OBJECTIVES: Discuss the distinguishing characteristics of crustaceans.

Describe the anatomy of a typical crustacean. Section 28-3 Crustaceans OBJECTIVES: Describe the anatomy of a typical crustacean.

Section 28-3 Crustaceans In crustaceans, the first two pairs of appendages are “feelers” called antennae, which bear many sensory hairs third pair of appendages are mouthparts called mandibles might bite and grind; filter feeding

Section 28-3 Crustaceans Appendages can vary greatly barnacles have delicate, feathery appendages for filter feeding others have legs for walking or swimming some modified for fertilization, carrying eggs, spearing prey

Section 28-3 Crustaceans Appendages are adapted for: the large claws catch prey; pick up, crush, and cut food- these are on the thorax 4 pairs of walking legs, also on the thorax Flipper-like swimmerets for swimming on the abdomen

Section 28-3 Crustaceans The paddle-like appendages and the final abdominal segment form a large, flat tail very powerful; a crayfish can snap forward, thus rapidly pulling the animal backwards “roly-poly” in Figure 28-22, page 620- pill bug (a crustacean)

Section 28-4 Insects and their Relatives OBJECTIVES: Describe and give examples of three classes in the subphylum Uniramia.

Section 28-4 Insects and their Relatives OBJECTIVES: Discuss the anatomy of a typical insect.

Section 28-4 Insects and their Relatives OBJECTIVES: Explain how insects communicate.

Section 28-4 Insects and their Relatives They lack closable spiracles and a waterproof coating on their exoskeleton thus they lose water easily therefore, they tend to live beneath rocks, in soil, or in other relatively moist areas

Section 28-4 Insects and their Relatives Class Chilopoda- centipedes these are carnivores that have in addition to their mouthparts, a pair of poison claws in their head region used to catch and stun or kill prey- other arthropods, earthworms, toads, small snakes, and even mice

Section 28-4 Insects and their Relatives Most centipedes in North America are 3-6 cm long; but some tropical species are brightly colored, and up to 26 cm Despite the name (which means 100 legs), they can have a variable number, depending upon how long they are

Section 28-4 Insects and their Relatives There is only one pair of legs per body segment except the mouth, which has the poison claws, and the last three segments (which are legless)

Section 28-4 Insects and their Relatives Class Diplopoda- these are the millipedes, and they do not have a thousand legs like the name implies they have 2 pairs of legs per body segment these are timid creatures, and are detritus feeders

Section 28-4 Insects and their Relatives Class Insecta- the insects have more than 900,000 species; new ones are being discovered in the tropics all the time 3 out of every 4 animals! three part body: head, thorax, and abdomen. There are 3 pairs of legs on the thorax

Section 28-4 Insects and their Relatives A typical insect has one pair of antennae, one pair of compound eyes on the head, two pairs of wings on the thorax, and uses a system of tracheal tubes for respiration Figure 28-26, page 623

Section 28-4 Insects and their Relatives Insects get their name from the Latin word insectum, meaning notched- refers to the division of their body into the three parts many insects, such as ants, have clear cut divisions- others such as grasshopper may not have body parts sharply defined

Section 28-4 Insects and their Relatives Feeding- insects have 3 pairs of appendages that are used as mouthparts, including a pair of mandibles (jaws) many shapes and varieties: grasshopper: cut / chew plants mosquito: tube pierces skin to suck blood (females only)

Section 28-4 Insects and their Relatives butterfly: long tube for sipping nectar bee: chewing and gathering nectar fly: spongy mouthpart used to soak up food

Section 28-4 Insects and their Relatives The saliva of female mosquitoes, which is injected when the mosquito “bites”, contains chemicals that prevent blood from clotting- also has chemicals that cause the itching bee body covered with many hairs that collect pollen

Section 28-4 Insects and their Relatives Chemicals in bee saliva help change nectar into a more digestible form- honey glands on the bee abdomen secrete wax, which is used to build storage chambers for food and others structures within a beehive

Section 28-4 Insects and their Relatives Movement- insects have 3 pairs of walking legs often equipped with spines or hooks for holding on, or used for defense may be used for jumping (fleas), or holding prey (praying mantis)

Section 28-4 Insects and their Relatives Movement- along with birds and bats, insects are the only living organisms capable of unassisted flight flight ability varies greatly; from slow butterflies to fast flies, bees, and dragonflies requires enormous energy, thus have oversized mitochondria

Section 28-4 Insects and their Relatives Insect societies- many animals form colonies, collections of individuals of the same species several types of insects for a special colony called a society separate individuals are dependent upon one another for survival

Section 28-4 Insects and their Relatives Insect societies- examples are termites, wasps, bees, and ants all called social insects they have a division of labor: 1) reproductive females 2) reproductive males 3) workers

Section 28-4 Insects and their Relatives Reproductive females = queen, typically there is only one, and usually the largest individual in the colony- page 625 termite queen may be 14 cm long, 10 times normal can produce more than 30,000 eggs a day!

Section 28-4 Insects and their Relatives The reproductive males function only to fertilize the queen’s eggs queen bee mates only once the successful males die after mating, and the unsuccessful males are ejected from the colony and soon perish (since they are no longer needed!)

Section 28-4 Insects and their Relatives The workers perform all colony tasks except reproduction: care for queen and eggs; gather and store food; build and maintain the colony’s home in bees, the workers are sterile females; in termites, the workers consist of males and females

Section 28-4 Insects and their Relatives Insect communication- may use sounds, visual, chemical, or other methods may be necessary to find mate male crickets chirp by rubbing their forewings together male cicadas buzz special membranes on their abdomen

Section 28-4 Insects and their Relatives Male fireflies turn a light producing organ in their abdomen on and off many insects can release chemicals that attract the opposite sex- called pheromones communication in non-social insects not near as complex

Section 28-4 Insects and their Relatives Queen bee produces a pheromone, called queen substance, that prevents the development of rival queens this substance makes the worker bees unable to lay eggs need a new queen? Feed the larvae a special diet

Section 28-4 Insects and their Relatives Honeybees communicate with sound and movement, as well as with pheromones worker bees are able to convey information about the type, quality, direction, and distance of food by “dancing” Austrian biologist Karl von Frisch

Section 28-4 Insects and their Relatives 1. Round dance- bee that has found food will circle first one way, then the other, over and over again (Fig. 28-32, p.627) tells others that food is within 50 meters, but not direction frequency of dance conveys quality of the food

Section 28-4 Insects and their Relatives 2. Waggle dance- the bee that has found food runs forward in a straight line while wiggling her abdomen, then circles around much like a figure eight food is more then 50 m away the direction of the dance tells the direction of the food source

Section 28-5 How Arthropods Fit Into the World OBJECTIVES: Describe how arthropods interact with other organisms in nature.

Section 28-5 How Arthropods Fit Into the World OBJECTIVES: Discuss how arthropods affect humans.

Section 28-5 How Arthropods Fit Into the World Such a large diverse group will play many roles in the natural world can be a direct source of food for many organisms either eating others or being eaten by them

Section 28-5 How Arthropods Fit Into the World Involved in symbiotic relationships Fig. 28-34, p.629 pores of our skin are home to thousands of harmless microscopic mites; no matter how much we clean our home, even our beds, there are millions of these dust mites

Section 28-5 How Arthropods Fit Into the World Agriculture would be impossible if not for bees, butterflies, wasps, moths, and flies that pollinate honey from bees; silk from silkworm moths shrimp, crab, crayfish, lobster used as a food source for humans

Section 28-5 How Arthropods Fit Into the World Grasshoppers and termites can also be eaten; they can also do considerable damage to crops and wood materials many insects and spiders are predators on other harmful species

Section 28-5 How Arthropods Fit Into the World Chemicals from arthropods extract of horseshoe crab blood is used to test purity of medications chitin from exoskeletons used to dress wounds and make thread for surgical stitches

Section 28-5 How Arthropods Fit Into the World The chitin may also be sprayed on fruit and frozen food to prevent spoilage the adhesive that barnacles use to attach themselves to rocks under water could be used in dentistry or underwater construction

Section 28-5 How Arthropods Fit Into the World Spider venom is being tested as a pesticide spider silk that could be used in making aircraft, helmets, bulletproof vests, and surgical thread

Section 28-5 How Arthropods Fit Into the World However good they are, they can also do considerable damage: parasites damage livestock and crops mosquitoes annoying bites and the spread of malaria and yellow fever

Section 28-5 How Arthropods Fit Into the World Biting flies carry diseases such as sleeping sickness and river blindness fleas carrying bubonic plague termites damaging wood locusts (grasshoppers) destroying crops