Invertebrates

Question 1

what are invertebrates?

Answer 1

animals that do not have a vertebral column or backbone

Question 2

name the four groups of arthropods

Answer 2

crustaceans, insects, arachnids and myriapods

Question 3

what are arthropods?

Answer 3

largest of the groups in the animal kingdom as it contains the largest number of species. each species has a segmented body, an external skeleton (exoskeleton) and jointed legs
hard exoskeleton allows them to live on dry land. when too big for their exoskeleton, they moult and grow a new one.

Question 4

state the characteristics of crustaceans

Answer 4

.body divided into a cephalothorax (head-thorax) and abdomen
.many have a chalky exoskeleton that provides a very hard and effective protection against predators
.two pairs of antennae
.compund eyes
.between five and twenty pairs of legs
.breathe using gills
.live in water, some live on land but return to water to breed. exceptions are woodlice and some land crabs
.examples: crabs, shrimps, crayfish and lobsters

Question 5

state the characteristics of myriapods

Answer 5

.centipedes and millipedes
.long bodies made up of many segments
.not divided into separate regions
.centipedes: one pair of legs on each segment, fast-moving carnivores, powerful jaws and can paralyse their prey
.millipedes: two pairs of legs on each body segment, slow-moving herbivores

Question 6

state the characteristics of insects

Answer 6

.bodies divided into three parts: head, thorax and abdomen
.on thorax three pairs of legs and many have two pairs of wings
.one pair of antennae on head and compound eyes
.breathe through holes in the sides of the thorax and abdomen called spiracles
.two reasons why they are so succesful on land is that they are covered in waterproof cuticle that stops them loosing too much water, and they can fly
.largest group within arthropods
.examples: beetles, flies, locusts, cockroaches, dragonflies, butterflies, moths, bees and wasps

Question 7

state the characteristics of arachnids

Answer 7

.bodies divided into two parts, cephalothorax and abdomen
.four pairs of legs and no wings
.no antennae
.several pairs of simple, not compund, eyes
.paralyse their prey with poison fangs
.able to weave silken webs with their spinnerets
.examples: scorpions, ticks and mites are also classified as arachnids

Question 8

state three ways in which arachnids look different from insects

Answer 8

arachnids have bodies divided in two parts while insects are divided into three parts, they have simple eyes and insects have compound. And finally, arachnids have four pairs of legs, while insects have three

Question 9

describe the features of insects that adapt them for living succesfully on land

Answer 9

they are covered by a waterproof cuticle that stops them losing too much water and they can fly