Lecture 11 -Arthropods - 2

Question 1

where are crustaceans found?

Answer 1

predominantly marine - some freshwater and terrestrial

Question 2

describe the primitive body from of a crustacean

Answer 2

• 2 pairs of attenae
• cephalon
• trunk segment and trunk appendage - used for food capture and respiration

Question 3

what is a cephalothoraxic carpace

Answer 3

covers the head and thorax meaning in some crustaceans you cant always see the difference between head and thorax

Question 4

how can the head be modified

Answer 4

1-3 thoracic appendages may be incorporated into the head e.g. mandible, first maxilla and second maxilla

Question 5

crustacean appendages

Answer 5

biramous - 2 branches which join into endopod (walking leg) and exopod (filamentous branch)

Question 6

describe a waterflea (daphnia)

Answer 6

• whole animal is covered by a carapace
• parthogenesis - babies are genetically identical to mother
• trasnparaent animals
• sex can be used when conditions are unfavourable and eggs are dropped to bottom of pond and hatch in better conditions

Question 7

why do barnacles have no abdomen?

Answer 7

• hox gene abdominal A is lost

Question 8

barnacle reproduction

Answer 8

• very large penises

- hermaphrodite

Question 9

how do barnacles avoid dessication

Answer 9

can completely close their valve - when water covers them their legs come out for feeding

Question 10

what is a sacculin?

Answer 10

a parasitic barnacle that attaches to crabs and feminise them change the behaviour of the crab to aid in the dispersal of the barnacles eggs

Question 11

what has been shown in crustacean reproduction in some species?

Answer 11

mate guarding - males carry female around until she is molting (capable of mating)

Question 12

crustacean larval stage

Answer 12

nauphilus larval stage

Question 13

body of myriapods

Answer 13

2 tagmata - head and trunk

- single pair of attenae

Question 14

describe centipedes body

Answer 14

• dorsoventrally flattened with legs projecting out the side
• well developed poison claw (maxilliped)

Question 15

describe millipedes body

Answer 15

body is more rounded and legs dangle from the bottom - lots of legs
- each segment has 4 appendages

Question 16

how do millipedes feed?

Answer 16

dont have posion claw because they feed on plant material

Question 17

how do millipedes defend themselves?

Answer 17

emit hydrogen cyanide and other chemicals

Question 18

how do millipedes breathe?

Answer 18

movement of air by muscles and diffusion through tracheoles - limits their size
- malphigian tubules absorb useful substances

Question 19

where are millipedes usually found?

Answer 19

in damp conditions because their cuticle isnt that well adapted to life on land