6. lesson Teeths Flashcards
Placoid scales (dermal denticles = little teeths) advantagdes?
Tough, protective and helps when swimming.
Scales don´t overlap.
They dont grow bigger, when the fish grows. Instead more scales are added.
How came teeth to be?
Teeth was an biological mutation, where scales was attached to the jaw. This went to be a very good mutation. Fish with teeth was better in surviving then the fishes without teeths.
The teeths are made of cartillage.
Does a shark have several rows of teeths?
Yeeees, when it looses one, other moves forward. That´s why we find a lot of shark teeths on the beaches.
Does a shark have several rows of teeths?
Yeeees, when it looses one, other moves forward. That´s why we find a lot of shark teeths on the beaches.
What keeps teeth sharp?
Some part of the teeths are made of softer material, which erodes slowly.
This keeps the teeth sharp.
What is paired fins?
Paired fins means, that the fish has the same fine on both sides of the body.
even ray and skates have paired fins, because the hold “wing” is a fin, which is found on the other side. They have bilateral symmetry.
What is a spiracle?
A spiracle is tubes, the fish uses to breath through. its especially smart for fish when they eat or (like our nose), or bottom-feaders there need to breath when the mouth faces the bottom.
The different kinds of Chondrichthyans giving birth?
They mature late and gove birth two few young at the time.
Oviparous - Egglaying, eggs are laid in leathery cases.
Ovovivparous - Eggs are formed and hatched inside the mother, and then borned alive. Sometime they eat there brothers and sisters, other mothers feed them with eggs, and some have an umbilical cord.
Viviparous - Shark pups are borned alive after developing in the mother.
What is Ampullae of Lorenzini?
That is small types in the body, which sences electric fields and water temperature.
In some way they can create images in their brain. Fx a shark can detect a fish breathing.
What is Elasmobranchii ?
its a subclass of Chondricththyans.
Sharks
skates, lay eggs, makes riples with their fins
rays, doesnt lay eg, flaps like a bird
How do you decide the sex of a shark?
They have extra pair of rolled up fins underneath their body.
female doesn´t
Holocephali
Includes the rat and elephant fish, which uses their nose to search in the setlement through electric senseory. Some doesn´t use their eyes.
Teleostomi
The bony fish. Humans are included here.
Includes Acanthodii, which is all instinct and considered and paraphyletic group. Marine and freshwater.
Acanthodians
Spiny fish, beacuse their fins where spiny.
