Nekton- Vertebrates Flashcards
nekton can ___ themselves (swim __ the water)
propel
against
____ are jawless fishes like lampreys and hagfish
Agnatha
Chondrichthyes= ____ fishes including ____ and rays
They have:
- _____ skeleton
- replaceable ___ ___
- ___ skeleton
cartilaginous
sharks
cartilaginous
tooth rows (lose their teeth)
dermal
_____ are bony fishes with teeth fixed in jaws (much more diverse than Chondrichthyes)
Osteichthyes
Why aren’t we sure about the phylogenetic tree of hagfishes/ lampreys?
really hard to find eggs/ young/ DNA of hagfish
- hagfish could be an outgroup, or might be sister taxa to lampreys
hagfish have an eel-like body, and ___ but no ___
teeth but no jaws
what are 3 distinguishing characteristics of hagfish?
- scavengers: they eat dead animals etc in deep waters- they burrow into the animal and eat it inside-out
- rough skin, can absorb nutrients through the skin (absorb from the dead animals they’re inside of)
- secrete immense amounts of slime for defense (hydrated collagen material, clogs gills of predators to deter them)
There are ~____ fish species in all habitats
30, 000
The form of fishes is related to their ___ and ____ ecology
What are the 5 forms? Give examples
locomotion and feeding ecology
- Rover- predators like tuna
- surface oriented- eat plankton (eg flying fish)
- Bottom fish- ie flat fish: eat small fish/ snails & create burrows
- Deep bodied- herbivores/ coral specialists eg butterfly fissh
- Eel-like
-
-
give an example of each
- acceleration eg barracuda (predator)
- cruising eg tuna (predator)
- maneuvering eg butterflyfish (herbivore)
most fish are ____, meaning they’re __-blooded
Some have evolved ___ to allow hunting in cooler waters (eg tuna)
poikilotherms
cold
endothermy (warm-blooded)
sharks are a ___-specialist, so they rely on their ___ to propel them and swim
cruise
tail
for most fish, swimming usually involves ____ of their entire body (thrust)
undulation
What’s a Mola mola ocean sunfish?
a massive fish (3 species) related to pufferfish
- slow-moving and deep diving- feed on jellyfish
- endangered b/c they’re easy to catch in our nets :(
How do sharks stay buoyant?
- they have cartilage as a skeleton, which is lightweight compared to mineral skeletons
- control buoyancy by fat storage in their liver
*sharks must keep moving to stay buoyant
Often, bony fish have bones and tissues that are more dense than seawater. How do they stay buoyant?
They use a swim bladder
gas is exchanged through a network of capillaries called the rete mirabile
exchange of gas in from the blood into the swim bladder across capillaries in the rete mirabile
T/F
blood flow is in the same direction as water flow in nekton
false
blood flow in opposite direction of water flow
“countercurrent exchange”
How do fish do oxygen exchange?
water flows over gill lamellae and oxygen diffuses into gills
sharks are ____, meaning their blood osmolarity is ~___ compared to seawater
isotonic
the same
do sharks need to drink water? Do they need to excrete solutes?
No because they’re isotonic
Usually don’t need to excrete solutes, but if they do, it’s via the rectal gland
Bony fish are __, meaning their blood has ___(fewer/more) solutes than seawater
hypotonic
blood has fewer solutes than seawater
Do bony fish need to drink water? Do they need to excrete solutes?
Yes, they need to drink water and then excrete the solutes
Solute excretion is over gills (via chloride cells)
t/f
some sharks can live in freshwater
true
Sharks can be Euryhaline or stenohaline. Explain what this means
Euryhaline= able to conserve urea & absorb salts, so these sharks can live in freshwater (found high in estuaries)
Stenohaline= unable to survive long-term in water fresher than 50/50
- known to enter estuaries, but they return to saltwater
Describe the teeth that sharks have
predatory sharks have teeth produced by a tooth bed (they’re temporary)
- dentine, but no root
- drop 1 tooth/ week minimum (great fossil record)
Sharks also have teeth in skin (dermal scales) to provide lightweight protection
Some sharks are filter-feeders, like the ___ shark and ___ shark. How do they eat?
Basking sharks and whale sharks
they use gill rakers (bars on gills with filaments that collect tiny particles)
they eat plankton like copepods, shrimp
Filter 2000-6000L/hr= they get huge!
whale sharks are ovoviviparous, meaning:
Why are whale sharks endangered?
they give birth to live young hatched from eggs inside the female
endangered b/c they’re hunted for fins and have a very long generation time
Different sharks have 3 different methods of reproduction:
1
2
3
give an example for each
- oviparous: lay egg cases that can wrap around any structure
- eg many sharks and rays - Viviparous: placental- give birth to live young
- eg bull shark - Ovoviviparous: produce eggs, which hatch inside the female –> give birth to live young
- eg whale shark
why don’t sharks have very sustainable populations?
they take a long time to reach reproductive age & don’t produce many young
Sharks have good hearing; explain how it works
their ears are behind their eyes
- hair cells= very sensitive to low-frequency sounds and have good directional hearing
How do sharks detect water vibrations?
Lateral Line system
- hair cells in fluid-filled canals down the head and trunk to detect water vibrations
Sharks have ampullae of lorenzini. What are they?
small pores filled with glycoproteins that detect electrical fields
Sharks have a good sense of smell through ___
nares
sharks have color vision and see well in __-intensity light with two specialized features:
- 2.
low
- tapetum locidum
- nictating membrane
What is the tapetum lucidum
a specialized feature of shark’s eyes to be able to see in low light
- a reflective surface behind the retina boots the visual signal in low light levels
What is the nictating membrane?
a cover over the shark eye to protect it from damage when feeding (like an eyelid- they feed very aggressively)
Which 3 categories fall into Nekton?
1 jawless fish (agnatha)
2. cartilaginous fish (sharks)
3. bony fish
sharks are ___ swimmers- the caudal fin provides ___, and lift is provided by ___ fins
cruise
thrust
pectoral
