Arthropods

Question 1

what are the subphyla of the phylum arthropoda

Answer 1

1) crustacea
2) hexapoda
3) myriapoda
4) cheliceriformes

Question 2

what percentage of all animals are arthropods

Answer 2

75%-80%

Question 3

outline some characteristics of arthropods in regards to their body plan

Answer 3

1) bilaterally symmertric
2) each body segment has a pair of segmented, ventrally attached appendages
3) head has compound eyes
4) cuticle exoskeleton of plates

Question 4

what are sclerites

Answer 4

plates which make up the exoskeleton made up from a cuticle

Question 5

how do arthropoda differ from annelids

Answer 5

• no hydrostatic skeleton
• no repeating organs in each segment
• no cilia
• usually seperate sexes

Question 6

what is arthropodization

Answer 6

organisms which are taxomically joined together by a single body plan

Question 7

what are the consequences sclerotisation

Answer 7

aka tanning which hardens the arthropods cuticle
- protection
- allow movement
- restricts growth
- restricts respiration and excretion

Question 8

outline the components of each body segment

Answer 8

1) large dorsal sclerite = tergite
2) large ventral sclerite = sternite
3) side regions are unsclerotised= pleura

Question 9

what is the cuticle divided into in arthropods

Answer 9

1) epicuticle
2) procuticle
- exocuticle and endocuticle

Question 10

what odes the cement and waxy layer of the cuticle allow

Answer 10

cement= lipoprotein protects against bacteria
waxy = prevents water loss

Question 11

what are articular membranes

Answer 11

articulation points joining sclerites which are thin and flexible cuticle allowing movement

Question 12

what are projections of sclerites called

Answer 12

apodemes

Question 13

what are condyles

Answer 13

points of contact or bearing surfaces between sclerites called condyles which help to take the weight away from muscles

Question 14

what hormone controlls the growth of arthropods

Answer 14

ecdysone

Question 15

outline the process of moulting

Answer 15

-enzymes digest the old endo cuticle
-the epidermis secretes new, soft cuticle beneath existing exoskeleton
- old cuticle splits along predetermined lines
- takes in water and body swells enlarging new cuticle
- new cuticle hardens by sclerotisation

Question 16

what are the dangers of moulting

Answer 16

• sometimes hard to withdraw from old cuticle
• prone to predation before new cuticle hardens

Question 17

what are the two methods of excreting waste in arthropods

Answer 17

1) nephridia = takes waster from coelom and excrete via special glands
2) malphigian tubes= attached to the stomach and lie inside the body cavity

Question 18

what is an ocelli

Answer 18

the simplest type of eye which is composed of a single lens and has no retina

Question 19

outline the characteristics of crustacea subphylum

Answer 19

• 70,000 species
• 3 tagmata = head, thorax and abdomen
• 5 pairs of cephalic appendanges

Question 20

what is a malostraca

Answer 20

a class from the subphylum crustacea with a basic body plan consisting off 5-8-6 body segments split into 3 subclasses
1) phyllocarida
2) hoplocardia
3) eumalostraca

Question 21

what are the three superorders from the subclass eumalostraca

Answer 21

1) syncarida
2) eucarida
3) peracardia

Question 22

outline the characteristics of the superorder eucarida from the subclass eumalostraca

Answer 22

• suspension feeders which form huge swarms
• major food source for whales, squid fish and birds
  -external gills

Question 23

outline the characteristics of the superorder decapoda from the subclass eumalostraca

Answer 23

• well developed carapace
• 3 pairs of maxilipeds used in feeding
• 5 pairs of peraeopods with one pair usually clawed

Question 24

what are the 4 infraorders of the suborder reptantia from the subclass eumalostraca

Answer 24

1) astacidae-
2) plainura- crawfish and spiny lobsters
3) anomura- 5th leg reduced on turned inwards
4) brachyura- true crabs

Question 25

outline characteristics of the subphylum myriapoda

Answer 25

11,500 species
- terrestrial athropods with 2 tagmata, cephalon and segmented trunk
- exoskeleton rarley has a wax layer
- gas exchange by tracheae and spiracles

Question 26

what are the two minor classes from the subphylum myriapoda

Answer 26

1) symphala- live in soil and lead mould similar to centipeded
2) pauropoda - microscopic inhabiting leaf mould and soil similar to milipedes

Question 27

what are the two main classes of the subphylum myriapoda

Answer 27

chilopoda = centipedes
diplopoda = millipedes

Question 28

outline the characteristics of chilopoda/centipedes

Answer 28

• numerous segmented unfused trunk sgements each with one pair of leggs
• ## first pair modified as clawed containing venom

Question 29

outline locomotion in centipedes

Answer 29

legs either side of the body are out of phase so as speed increases fewer legs on the ground which increase speed but gives weak forward motion

Question 30

outline the characteristics of diplopoda/millipedes

Answer 30

trunk segments fused into pairs each baring 2 pairs of legs
lack claws or venom glands

Question 31

outline locomotion in millipedes

Answer 31

legs positioned ventrally with body close to ground
legs in phase and majority in contact with ground producing slow but powerful forward movement