ARTHROPODS

Introduction to the Arthropoda... the REAL rulers of the Earth...

By nearly any measure, the most successful animalsanimals on the planet are the arthropods. They have conquered land, \sea and air, and make up over three-fourths of all currently known living and fossil organisms, or over one million species in all. Since many arthropod species remain undocumented or undiscovered, especially in tropical rain forests, the true number of living arthropod species is probably in the tens of millions. One recent conservative estimate puts the number of arthropod species in tropical forests at 6 to 9 million species (Thomas, 1990).

Arthropod classification Arthropods are classified based on –The number and structure of their body segments –Number and structure of their body segments Especially their mouth

3 major groups of arthropods Crustaceans Spiders and their relatives Insects and their relatives

List the Characteristics of Arthropods

Economic importance/ DISADVANTAGES

Economic importance/ ADVANTAGES

Introduction to Insect Anatomy

Insects are an extremely diverse type of animal. All have an external supporting structure, called an exoskeleton and all have bodies that can be divided into three major areas: the head, the thorax and the abdomen. The head carries the eyes, mouthparts and a pair of sensory antenna. The thorax provides support for three pair of legs and usually two pair of wings. Some insects, such as ants and termites, do not have wings. The abdomen contains most of the insect's digestive system and it reproductive organs. Parts vary greatly by species, but the grasshopper is somewhat representational.

Special modification

The most distinguishing characteristic of an insect's head is the mouthparts. They may be designed for chewing food, for sucking it or lapping it up. The housefly uses its it's mouthparts are used for mopping; up liquid food. The end of the labium functions like a sponge. A butterfly sucks up its food through a part of the maxillae that forms a tube. The mosquito also sucks ups its food. All of its mouthparts, except the labium, form a needle-like tube called a fascicle. The ground beetle is a carnivore; it has large mandibles adapted for piercing and cutting prey.

Tagmata Definition Tagmatization

Appendages Definition Evolutionary advantage Special adaptations –Mandibulates –Chelicerates

Appendages - continues What is the difference between biramous leg in a crustacean and a uniramous leg in an insect. Draw a simple diagram of the two.

The legs of all insects are made up of the same basic part femur, trochanter, coxa, tibia and tarus, but they can differ considerably.

Insect Leg Anatomy rear leg of a cockroach. It is long and lean, made for running - as anyone who has watched them scamper across the kitchen know. They have spines which point backward. They are used for holding onto surfaces.

Rear leg of the grasshopper. It has a large, strongly-muscled femur to help it leap into the air. Such leaps are often used to get it off the ground so that it can start flying.

The Honeybee's back legs are covered with hair. Pollen sticks to the them and is collected into a special area on the leg called a pollen basket.

The Mole Cricket's legs are short and spade-like, making them especially useful for digging.

Exoskeleton Part of arthropods success can be attributed to the presence of the exoskeleton. Definition Composition

Explain ecdysis Why does the animal puff up?

Characterize segmentation in arthropods cephalothorax

Respiration Arthropods are quick active animals. They have large oxygen needs in order to sustain the high levels of metabolism required for rapid movements.

3 types of respiratory structures Tracheal tubes Spiracles Book lungs

Senses Quick movements of arthropods enable them to respond to a variety of stimuli. Movement, sound, and chemicals can be detected with great sensitivity by special structures.

Distinguish between the compound eye and the simple eye Compound eye –Ommatidia –Rhabdom

Pheromones

Nervous systems Well developed Brain Ventral ganglia Difference between brain of arthropods and vertebrates

Excretion Malpighian tubles

Muscles Well developed In humans, the muscles are attached to the outer surfaces of internal bones In arthropods, the muscles are attached to the inner surface of the exoskeleton. Also, the muscle is attached to the exoskeleton on both sides of the joint.

Reproduction Separate male and female Reproduce sexually Parthenogenesis

Subphylum: Chelicerata Class Arachnida –Order Scorpiones –Order Araneae –Order Acari –Order Opiliones Class Merostomata Class Pycnogonida

SubPhylum Crustacea Subphylum Uniramia –Classes Diplopoda and Chilopoda –Class Insecta

Class Arachnida Arachnids Includes spiders, ticks, mites, scorpions, and daddy longlegs.

Scorpiones Scorpions recognized by their many abdominal body segments and enlarged pincers Long tail with venomous stinger at the tip Live in warm, dry, climates Eat insects and spiders Use the poison in their stingers to paralyze large prey

Order: Araneae Spiders Important predators of insects and other small animals 2 body regions 6 pairs of jointed appendages –Chelicerae –pedipalps No antennae

Spiders continued Extracellular digestion Spinnerets Not all spiders spin webs –Wolf spider hunts it prey - no web Poison glands –Black widow and brown recluse

Order Acari: The Mites Most are small, less that 1mm Some are predatory Other are internal and external parasites Mites that live on humans

Ticks Ectoparasites Diseases associated with parasites:

Order Opiliones Daddy Longlegs Also called harvestmen Predators of insects, snails, worms, and other arachnids.

Class Merstomata Horseshoe crabs Ancient group Fossils identical to Limulus found 220 million years ago

Subphylum Crustacea

Characteristics of Crustaceans

Terms Labyrinth Carapace Swimmerets Uropods telson

Insect reproduction Mate only once or at most a few times during their lifetime Most lay a large number of eggs, which increases the chances that some offspring will survive long enough to reproduce

Metamorphosis A series of chemically controlled changes in body structure from juvenile to adult. My be complete or incomplete Usually 4 stages

Incomplete metamorphosis Egg Nymph adult