Fish Flashcards
What is paedomorphosis?
Sexual maturation in juvenile form
What are the 5 distinct characteristics of chordates?
- Notochord
- Dorsal nerve cord
- Pharyngeal slits
- Endostyle
- Post-anal tail
What additional characteristics do vertebrate carry?
*Not the chordate characteristics
- Vertebral column “backbone”
- Cranium
- Tripartite brain
- Kidneys
- Endoskeleton (bone or cartilage)
Fish are a highly diverse range of species. There is currently an estimated ________ species in total. This represents >___% of living vertebrates.
Water is ____ times denser than air.
Water has _____ concentration of oxygen.
(1) ~28,000
(2) 50
(3) 800
(4) 1/20th
Name at least three characteristics of the class ostracoderms.
Are they extinct or extant?
- Jawless fish
- All covered by bony plates
- Bony plates acted like jaws
- Notochord was probably the main axial support
EXTINCT - during the late Devonian mass extinctions
What is the general feeding behaviour of hagfish?
- They feed on dead marine mammals, tie themselves in knots to increase grip.
Name at least three lamprey features
- Single nasal opening
- Rudimentary Thyroid Gland (endostyle)
- Has a kidney
- Lampreys can osmoregulation in freshwater (specialised chloride cells)
- 7 pairs of gill pouches
- Large, well developed eyes;
What are the key features of the gnathostomes evolutionary step?
- Upper and Lower jaws; Expand the niches which can be used; grasp hold/tear away; allowed jawed vertebrates to become apex predators
- Paired fins; better control during swimming
What classes does the phyla gnathostomata filter in to?
- Placodermi (EXTINCT)
- Chondrichthyes
- Osteichthyes
The class chondrichthyes is made of 2 subclasses. What are they?
- Elasmobranchs
- Holocephali
Name at least three characteristics of the subclass Holocephali
- Generally deep marine fish >80 metres deep
- Holocephali have a single gill opening
- Cartilaginous skeleton
- A “whip” like tail
- Generally, bottom feeders
- No obvious teeth, but large flat plates
Includes Chimaeras/Ratfish
There are 3 different lineages of sharks & rays. What are they? Briefly explain.
- Squaloid sharks (~80 species) such as dogfish. No anal fin .
- Galeoid Sharks (~280 species) These are dominant, include the great white, hammerhead & whale shark. Have an anal fin
- Batoidea (Sharks and Rays)
What are some key features of chondrichthyes (at least three).
- Endoskeleton (cartilaginous)
- Buoyancy
- Movement
- External coverings
- Feeding
- Reproduction
Name at least three characteristics of Elasmobranchs
- Fusiform body or dorsal-ventrally depressed
- Heterocercal caudal fin (tail)
- Male has claspers for reproduction
- Ventral mouth
- Placoid scales
- Endoskeleton entirely cartilaginous
- Internal fertilisation
- High concentrations of urea and trimethylamine oxide in blood
- They are negatively buoyant; no swim bladder; keep swimming to stop sinking; oily livers that can aid buoyancy (squalene oil/shark oil)
In chondrichthyes, name the movement caused by the following fins.
(1) Paired fins control pitch.
(2) Caudal fin.
(3) Dorsal and anal fins.
(1) up and down - PITCH
(2) thrust forward - YAW
(3) ROLL
The caudal fin (tail) can otherwise been known as a ___________ tail. It helps to give ____ to the fish as it swims along.
Heterocercal tail
“lift”
Sharks are highly streamlined and can swim up to _____km/hr^-1.
Their skin is covered by ______ scales - which appear like tiny tooth like scales.
The scales have a hard outer surface, _______, which is similar to tooth enamel.
55km/h^-1
PLACOID scales
Vitrodentine
Predatory sharks actively search for food using a variety of senses. What are they?
- Chemoreception; highly sensitive smell & olfactory system
- Vision; special adaptation for vision in poor light
- Mechanoreception
- Electroreception
Electroreceptors are modified hair cells of the lateral line. Sharks have these on their ______. Skate and rays have them on their _______.
head
pectoral fins
Hammerhead sharks use the wide head to spread the distance between _________. Previously thought to be for ________ or vision. The metal on a shark cage may confuse the shark and rarely attacks the metal structure.
electroreceptors
olfaction
Manta rays are filter feeders. They have peculiar ______ fins to direct food into the mouth.
cephalic
Name at least three features of reproductive strategies in elasmobranchs
- Sophisticated breeding mechanisms
- All fertilisation is internal
- Males have specialised CLASPERS
- Small sharks: male wraps round female
- Larger sharks: male bites into back or onto fin, often scar marks are left on female.
What is lecithotrophy?
The yolk supplies most of the nutrients to embryo. As described as oviparous egg is deposited outside the body.
Example: dog fish egg/mermaids purse
Embryo can be seen developing within egg and will hatch out as fully formed fish.
Proteinaceous case around the egg allows it to become tangled in sea weed etc.
What is matrotrophy?
Female reproductive tract supplies nutrients.
Ovoviviparous & viviparous: Young is born fully formed.
There is a range of methods of nourishment, this has evolved separately in different classes of animals.
