Phylum Arthropoda

Arthropods are the most successful animal phylum in terms of species diversity, distribution, and sheer numbers

coelomate

body segmentation( modified metamerism)

hard exoskel

jointed appendages

Arthropodia segmentation

often fuse into three tagmata (anatomical areas) in the adult stage

head- contains segments with feeding and sensory activities

abdomen- contains segments with locomotor and or reproductive activities

cephalothorax

head and thoracic segments fused

the body of an arthropod is completely covered by the

cuticle

an exoskeleton of arthropod is made out of

protein and chitin

exoskeleton

strong, protects the animal and provides points of attachment for the muscles that move appendages.

thick and inflexible in some regions, such as crab claws, and think and flexible in others, such as joints

ecdysis

in order to grow, an arthropod must molt its old exoskeleton and secrete a larger one

leaves the animal temporarily vulnerable to predators and other dangers

its relative impermeability to water helps prevent desiccation and provides support on land

arthropods moved to land after the colonization of land by plants and fungi

Respiration

terrestrial arthropods generally have internal surfaces specialized for gas exchange. For example, insects have tracheal systems, branched air ducts leading into the interior from pores in the cuticle.

Subphylum Chelicerata

Limulus- horseshoe crab

Argiope- garden spider

Limulus- horseshoe crab

Argiope- garden spider

both contain one pair of_______ and one pair of ______.

________ and ________ are absent

Both contain one pair of chelicerae, one pair of pedipalps. Antennae and mandibles are ABSENT.

Subphylum Crustacea

Cabarus- crayfish

Cabarus- crayfish

found where?

contain two pairs of ______, 1 pair of ________

primarily found in aquatic environments.

contain two pairs of antennae, one pair of mandibles

Class insecta

Romalea- grasshoper

Romalea- grasshoper

found?

contain one pair______ and one pair_______

they are found in terrestrial environments.

contain one pair of antennae and one pair of mandibles

CRAYFISH ANATOMY

gills used for what?

located where?

feathery gills like under the lateral extensions of a large, expanded exoskeletal plate called the carapace

carpace

expanded exoskeletal plate

small angular structure located just under the carpace near the posterior portion of the thorax

heart

Internal anatomy of crayfish

large digestive glands fill much of the body cavity. the intestine extends from the stomach through the tain to the anus. the green glands lie near the brain in the head.

thin threads leading out from the heart

arteries

When blood collects in sinuses around the heart, the heart relaxes and these holes open to allow the heart to fill blood. the holes then close and the blood is pumped through the arteries which distribute it around the body. blood seeps back to the heat, since no veins are present

open circulatory system

green glands

excretory organs

long tubular structures that resemble nephridia but are compacted into a glandular mass.

Waste and excess water pass from these glads to the outside of the body through pores at the base of the antennae on the head.

brain

lies in the midline with nerves extending posteriorly fusing to form central nerve chord

How does the pattern of segmentation differ in the crayfish and the earthworm

crayfish has 3 distinct parts while the earthworm has septa that divides the body cavity

metamerism

condition in which body parts are repeated serially along the longitudinal axis of the body.

analids and arthropods

since all of the appendages of an animal such as the crayfish are believed to have evolved from the same basic ancestral structure they are said to be _____

homologous

because each appendage is homologous to the others on the animal, they demonstrate

serial homology

ABDOMEN APPENDAGES

uropods, swimmerets

uropods

1 pair on abdomen

biramous appendages that together with the medial telson make up the tail fan which is used in rapid escape movements and in fanning the eggs and young

swimmerets

5 pairs on abdomen

biramous, used for swimming

anterior two pairs are modified as copulatory organs in the male

their grooves direct sperm into the female's seminal receptacle. In the female, the swimmerets are also used t hold the fertilized eggs for incubation

THORAX APPENDAGES

walking legs

maxillipeds

walking legs

5 pairs on throax

uniramous; all but the last also bear gills

the first pair are the chelipeds and bear the large pincers (chelae)

the second and third pair also possess small pincers at their tips

maxillipeds

3 on thorax

biramous; used in food handling and chemosensation. The last two pairs have gills attached

HEAD APPENDAGES

Maxillae

Mandibles

antennae

antennules

Maxillae

2 pairs on head

biramous; used for food handling

second pair bears gill bailers which generate respiratory water currents through the gill chambers

mandibles

1 pair on head

uniramous

shred food for swallowing

antennae

1 pair

biramous; chemosensation

nephridiopore drains the green gland

antennules

1 pair on head

biramous

chemosensation

equilibrium

SUBPHYLUM CRUSTACEA

most marine, some freshwater, few terrestrial

free living even though some are parasitic

bodies of crustacean consist of two tagmata

cephalothorax, abdomen

cephalothorax

covered by a caprice and contains appendages used in sensing moving and feeding

contains two pairs of antennae, one pair of mandibles, 5 pairs of walking legs

abdomen

visceral functions

contains appendages used in moving

all crustaceans have two pairs of ______, 2 pairs of _____, a pair of ______, and a pair of ______ ____ commonly found on stalks

2 pairs of antennae, 2 pairs of maxillae, a pair of mandibles, pair of compound eyes

maxillla

one of the constituents of crustacean mouth parts

lie just behind the jaws and aid with detection and manipulation of food

serial homology

arthropods evolved from an annelid-like ancestor containing identical appendages

during this evolutionary process some metameres and appendages became specialized to accomplish different roles

the appendages are thus said to have serial homology. they are homologous since they are evolved from the same ancestral structures and serial since they are metameric

CLASS INSECTA

grasshopper (romalea)

only winged invertebrates

most successful species are small in size and have a great reproductive capacity

terrestrial

what sets insects apart from crustaceans

insects have one pair of antennae and crustaceans have 2 pairs

Insect body plan

have one pair of antennae and one pair of mandibles

thorax

usually has three pairs of walking legs and one or two pairs of wings

abdomen contains

most internal organs and specialized structure for reproduction

insects have

3 part gut

insects have what kind of appendages

unbranched appendages

Insect bodies divided into three_____

tagmata

head: containing appendages used in sensing and feeding

thorax: containing appendages used in moving

abdomen: containing no appendages and having visceral functions

Respiration in insects

uses a system of internal tubes- tracheae and sacs delivering oxygen directly to cells. Air is taken in through openings called spiracles (small openings in elastic air tubes)

digestive tract

narrow esophagus leading from the mouth expands into a large crop used for food storage

crop empties into

stomach where digestion takes place

gastric pouches

ceca

six pairs of these fingerlike extensions that connect to the digestive tract where the crop and the stomach meet.

these pouches secrete digestive enzymes and aid in food absorption.

food passes from the stomach to the

intestine then into the rectum and out the anus

hemocoel

space between the body walk and the digestive tract

excretion in insects

accomplished via Malpighian tubules

Malpighian tubules

blind ending tube like appendages of the intestine that open at the border between the mid and hindgut

as the hemolymph circulates in the hemocoel near these malpighian tubules, the uric acid is actively transported and discharged into the hindgut, from where the excretory products are passed with the feces

SUBPHYLUM CHELICERATA

named for clawlike feeding appendages called chelicerae which serve as pinchers or fangs. In their cephalothorax they contain one pair of chelicerae. this is followed by one pair of pedipalps and 4 pairs of walking legs.

lack antennae and mandibles

limulus- horseshoe crab

argiope- garden spider

Bodies of chelicerata are divided into two magmata

cephalothorax- locomotor, sensory, feeding appendages

abdomen- visceral functions

Horseshoe crabs

do not have hemoglobin but rather hemocyanin to carry oxygen in their blood

horseshoe crab blood contains

amebocytes which can be harvested for medical applications

Horseshoe crab exoskeleton

tough and leathery

must be molted periodically as the animal grows

divided into two regions: cephalathorax, abdomen

cephalothroax, abdomen

bears six pairs of spines along the sides and on its ventral side has six pairs of flat, plate-like appendages.

carpace

covering the cephalothorax dorsally and laterally

hard

concave below and convex above

chelicerae

small

used for food manipulation

1st pair of appendages

pedipalps

second pair of appendages

walking legs, chelae

next 4 pairs

gnathobases, chilaria

all appendages except the chelicerae have spiny masticatory processes called this on the basal segments.

the chelae of the appendages pick up food and pass it to the gnathobases.

between the last pair of walking legs is a small rudimentary pair of appendages called the chilaria.

genital operculum

houses openings of the genital pores

Genital pores

2 on the underside of operculum

telson

tail used for bracing when the animal is burrowing or plowing through the sand or in righting itself when turned over

anus located ventrally at the proximal end

book gills, lamellae

leaf like folds

in life the plates and lamellae fan back and forth like the pages of a book in a breeze. because of this characteristic the collective structures are called book gills.

simple and compound eyes

later cpd eyes

median simple eyes

Spiders inject

poison from glands on the chelicerae to immobilize their prey which chewing their prey, spill digestive juices into the tissues and suck up the liquid meal

Arachnid cephalothorax has

6 pairs of appendages

-4 pairs of walking legs

-pair of pedipalps function in sensing or feeding

chelicerae usually function in feeding

how is gas exchange carried out in spiders

book lungs

silk protein

produced as a liquid by abdominal glands and spun by spinnerets into fibers that solidify

exoskel

hard, thin, chitinous, somewhat flexible

tagmata

cephalothorax and abdomen which includes the pedicel (slender waist)

cephalothorax

spiders do not have compound eyes

they have 6 to 8 ocelli (simple eyes) which can't detect motion so they rely more on tactile cues

sensory hairs

all parts of body have

fangs

2

used to eject poison from its poison gland

pedipalps

6 joined and sed for gripping prey

in the male it is modified as an intermittent organ to transfer sperm to the female

basal parts are used to squeeze and chew food

walking legs

4 pairs

each leg is made up of seven segments as follows : coxa, trochanter, femur, patella, tibia, metatarsus, tarsus

tarsus has claws and a tuft of sensory hairs at its terminal end

gas exchange

occurs between the blood circulating inside the lamellae and the air flowing in the spaces between the lamellae

tracheal spiracles

opening into a small chamber from which tracheal tubes extend into the body

epigynum

a chitinous plate which is located on the ventral mid line between the spiracle, conceals the female genital pore

3 pairs of spinnerets on a raised surface

book lungs

held apart by bars so that there are always air spaces between them

complete metamorphosis

passage through 3 different stages

larva hatches out of the egg

feeds and grows undergoing several molts

after the larva reaches maximum size, it molts and immediately undergoes a transformation into a non feeding stationary pupa.

pupal case splits open and the adult emerges

pupa

radical reorganization occurs. most of the larval tissues are broken down completely and replaced by adult structures concurrently formed from the division and differentiation of strategically situated clusters of embryonic cells called imaginal discs.

clusters were formed in the embryo but remain undifferentiated during the larval stage

incomplete metamorphosis

the immature form that somewhat resembles the adult transforms stepwise with each molt to reach the adult form.

adult never molts

larva

wormlike

nymph

resembles the adult but its head is disproportionately large and its wings are rudimentary.

as it feeds and grows it molts and with each molt it more closely approximates the adult form. finally after the last molt it is an adult with fully functional wings and a reproductive system.

naiad

in aquatic species the naiad, as the immature stage is called, looks less like the adult and usually has modifications like gills for aquatic life. Otherwise its development proceeds as for terrestrial species.

ex:odonata (dragonflies) and Ephemeroptera (mayflies)

exoskeleton

all insects have a exoskel composed of chitin and proteins which have been made tough and rigid through a chemical process called sclerotization.