nekton&fisheries

Question 1

what are the most numerous (specieas and abundance) vertabrate in the nekton?

Answer 1

fishes (30.000)

Question 2

oceanic nekton is difficult to study due to ….

Answer 2

1. fats swimming speeds
2. complex migration patterns
3. large distribution patteren

Question 3

nekton includes only vertebrate but no invertebrate; true or fals?

Answer 3

false;

as well invertebrates as vertebrates

Question 4

give two example for invertebrates

Answer 4

squid
cephalopodes
crustaceans

Question 5

give two example for vertebrates

Answer 5

reptiles (marine turtles) and marine mammals (whales, seals)

Question 6

nekton is the top predator of the oceanic system : true or false

Answer 6

true

Question 7

what are adaptions of oceanic nekton

Answer 7

locomotion 
echolocation 
defense and camoulflage 
migraton patterns 8food or mating/nursing)
buoyancy

Question 8

how can nekton swim actic?

Answer 8

imprtat of staying neutral –> high density areas (bone) need to be countered by low density areas in the body (fat)

Question 9

what can positively contribute to buoyancy

name 3

Answer 9

gas/swim bladder
gas filled cavities (lungs)
gas trapped in feather/fur
lipid storage  in muscles /liver 
fins
fat layer (blubber)

Question 10

what is the difference betw. swim bladder and filled bladder?

Answer 10

swim bladder: coupled to oeasophagus –> release ad refill aire
-> allows to regulate depth

filled bladder: cannot remove/refill air –> cannot regualte depth, species has to stay at one level

Question 11

do sharks have a swimmblader?

Answer 11

no they dont they stabilize them and they have a filled liver

Question 12

what are the two type of fin movements?

Answer 12

lateral fin movement

dorsoventral fin movement

Question 13

name sense organs of nekton animals

- what are they for?

Answer 13

lateral line sensory organ (chnages in wtaer pressure)

echolocation( detection of prey)

Question 14

what is the migration of the two freshwater eel types?- name the two types and from where they come from and where they go to.

Answer 14

european eel
american eel

migrate betw. freu and marine water
- breed in sargasso sea

migrate to rivers in either north america or europe

Question 15

migrate route of grey whales

Answer 15

migrate to the arctic ocean for feeding

nursery in warm waters (californian coast)

Question 16

what are the two main groups of nektonic crustaceans

Answer 16

krill and swimming crabs

Question 17

what are the main 2 gourps of nektonic marine reptiles. are they poikilo or homoiotherm?

Answer 17

sea snakes and turtels

poikilo therm

Question 18

what are the main 2 gourps of nektonic cephalopodes?

Answer 18

squid and cuttlfish

70% cuttlefish

Question 19

krill distribution: mainly on the south or nort hemisphere?

Answer 19

north

Question 20

what are the three classes of fish?

Answer 20

agnatha (kieferlose)
chondrichthyes (knorpelfische)
osteichthyes (knochenfische)

Question 21

chrondrichthyes and osteichthyes do not both have a swim bladder, who of them have a swim bladder

Answer 21

osteichthyes

Question 22

what is the largest marin emammal?

Answer 22

baleen whales (bartenwhale)

Question 23

migration pattern of humback whales : feeding and nursing where?

Answer 23

migration all over the globe
e.g.
antarctica for feeding
nursery grounds = warmer condition e.g. great barrier reef

Question 24

what are characteristics of marine mammals?

3

Answer 24

homoitherm
breath with lungs
nurse their offspring

Question 25

name three different types of fishery

Answer 25

artisanal
commercial
industrial 
offshore 
inshore

Question 26

what is a fishery definition

Answer 26

human and biological component of a fish harvest system

Question 27

why is fishery important?

Answer 27

because fish is an important part in the average diet of many countries (greenland, indonesian islands)

Question 28

how many fish speciea re already fully exploited ? (2004)

Answer 28

52 %