yes,sometimes
No, blackbirds do not use external fertilization; they reproduce through internal fertilization. Female blackbirds lay eggs after mating with a male, and fertilization occurs inside the female's body. The female then nests and incubates the eggs until they hatch.
External, because they lay eggs.
what two classes of vertebrates use external fertilisation
frogs use external fertilisation so the sperm is released into the water and the eggs are are released into water then the sperm fertilises the eggs
spiders
Fish use outer fertilization because they are not Mammals , which use inner fertilization . Mammals generally bear live young , with few exeptions . Fish and other cold blooded animals lay eggs which are fertilized outside the body , again with few exeptions .
Yes
Yes.
It is external because we all know that fish lay eggs and they lay eggs in their habitat so its meant to say that the fish, develop their embryo inside the egg and also where it is hatch.
Most fish use external reproduction, where eggs released by the female are fertilized by the male outside of their bodies. The fertilized eggs develop into larvae and eventually hatch as juvenile fish. Internal reproduction, where fertilization occurs inside the female's body, is rare among fish species.
Lions are mammals, and use internal fertilisation.
Seadragons are like seahorses in that it is the male who carries the eggs The female will deposit up to 250 eggs (bright pink) onto the males tail where the eggs attach themselves to a "brood patch" where they will stay for the next 6 to 8 weeks where they receive oxygen from "cups" on this brood patch and they become "fertilised" which is external