2 - Fishes Flashcards
In oceans no light beyond
1000 meters
Anglerfish adaptations
total darkness so:
- release mate attracting pheromones
- glowing bulb used of catching food
Desert pupfish
can withstand temps up to 45 degrees C
Crocodile icefish
- blood lacks red blood cells and haemoglobin
- clear blood
- contains anti-freeze chemical that prevents build up of ice crystals
When did this adaptive radiation begin
500mya
Ostracoderms
“fish” = oldest craniata
Teleostei
Most fish on planet now
Fish are ancestors of what
all other vertebrates
Subphylum craniata main characteristic
Skull that surrounds 3 part brain
Olfactory organs
Eyes
Inner ear
Subphylum craniata 2 infraphyla
- hyperotreti (hagfish)
2. vertebrata (vertebrates)
Infraphylum hyperotreti (hagfish) characteristics
Jawless Skull of cartilage Lack vertebrae and retain notochord No paired appendages Mouth with 4 pairs of tentacles Olfactory sacs open to mouth cavity 5-15 pairs of pharyngeal slits Ventrolated slime glands Tough, leather-like skin
Hagfish slime
Reacts with water to become slippery
Important for eating dead prey
More about hagfish
- Marine
- scavengers that feed off dead or dying organisms
- skin is used as leather
- 60 species
Superclass petromyzontomorphi class
class petromyzontida (lampreys)
Lamprey characteristics
- sucking mouth with teeth and rasping tongue
- 7 pairs of pharyngeal slits
- blind olfactory sacs
- true vertebrates but have ancient features
- 41 species
- marine and freshwater
- Some parasitic (ex: on lake trout) some not
- Complicated life style
- some are invasive species
Sea lamprey control programs
barriers, traps, lampricide
Ostracoderms are what
several classes of jawless fish
Ostracoderms characteristics
- 400 mya
- bony armour
- bottom dwellers
- probably filter feeders
- extinct
Superclass gnathostomata are what
jawed fishes
Gnathostoma 3 classes
chodrichthyes, actinopterygii, sarcopterygii
Importance of jaws
- led to predatory lifestyle in many fishes
- more efficient feeding so more offspring and exploitation of new habitats
- set stage for adaptive radiation of fishes
Class chondrichthyes 2 subclasses
elasmobranchii, holocephali
chondrichtyes characteristics
- tail fin with large upper lobe
- cartilaginous skeleton
- placoid scales ()
- lack opercula and a swim bladder or lungs
- Sharks, skates, rays, ratfishes
Placoid scales
skin feels like sandpaper, point posteriorly to reduce friction while swimming
Subclass elasmobranchii
sharks, rays and skates
820 species
375 mya (devonian)
Whale sharks
largest sharks but filter feeders
Subclass holocephalii
350 mya
operculum present
only surviving group is order chimaeriformes
Chimaeriformes
ratfish and elephantfish
Why are sharks endangered
Take a long time to reproduce/reach sexual maturity, exhibit some of the longest gestation times and maternal investment
