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Transcript of Biology - Chapter 28 “Arthropods” Introduction to Arthropods l Phylum Arthropoda - vary...
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:
1. Tough exoskeleton – shed to allow for growth (molt)a. Protectionb. Prevent water lossc. Made up of chitin (protein)
2. Series of jointed appendages in pairs3. Segmented body – head, thorax, abdomen
Introduction to Arthropods
4. 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 ArthropodsDevelopment through Metamorphosis:
1. Incomplete metamorphosis eggs hatch to nymph (kid) to adultexamples: 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. Cephalothorax2. Abdomen
Introduction to Arthropods2. 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 adultMoths, 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 esophagusAbdomen- 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 Arthropods3 Subphylums
1. Subphylum Crustacea– includes crabs, shrimp, crayfish
Crustaceans
Main body parts are the head, thorax, and abdomenin 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 – centipedes3. Class Diploda -- millipedes
Section 28-2Spiders 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 28-2Spiders 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 28-2Spiders 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 28-2Spiders and their Relatives
Once captured:1. Hollow fanglike chelicerae inject paralyzing venom
2. Mouth introduces enzymes3. Enzymes break down tissue4. Spider sucks up the liquefied tissues with esophagus and specialized pumping stomach
Section 28-2Spiders 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 28-2Spiders 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 28-2Spiders 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 28-2Spiders 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 28-2Spiders 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!
Section 28-3Crustaceans
OBJECTIVES:–Discuss the distinguishing characteristics of crustaceans.
Section 28-3Crustaceans
OBJECTIVES:–Describe the anatomy of a typical crustacean.
Section 28-3Crustaceans
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 28-3Crustaceans
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 28-3Crustaceans
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 28-3Crustaceans
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 28-4Insects and their Relatives
OBJECTIVES:–Describe and give examples of three classes in the subphylum Uniramia.
Section 28-4Insects and their Relatives
OBJECTIVES:–Discuss the anatomy of a typical insect.
Section 28-4Insects and their Relatives
OBJECTIVES:–Explain how insects communicate.
Section 28-4Insects 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 28-4Insects and their Relatives
Class Chilopoda- centipedesthese 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects and their Relatives–butterfly: long tube for sipping nectar
–bee: chewing and gathering nectar
–fly: spongy mouthpart used to soak up food
Section 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects and their Relatives
Insect societies- examples are termites, wasps, bees, and ants–all called social insects–they have a division of labor:1) reproductive females2) reproductive males3) workers
Section 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 28-4Insects 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 WorldOBJECTIVES:
–Describe how arthropods interact with other organisms in nature.
Section 28-5 How Arthropods Fit Into the WorldOBJECTIVES:
–Discuss how arthropods affect humans.
Section 28-5 How Arthropods Fit Into the WorldSuch 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 WorldAgriculture 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 WorldGrasshoppers 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 WorldChemicals 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 WorldThe 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 WorldSpider 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 WorldHowever 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 WorldBiting flies carry diseases such
as sleeping sickness and river blindness
fleas carrying bubonic plaguetermites damaging woodlocusts (grasshoppers)
destroying crops