NIGG3RS, or placenta
If the animal comes from an egg it will get its nutrients from the yolk. If it is a mammal it will get it from the umbilical cord.
yolk
It's a sack and not an egg but the primary food source, the only one, is the placenta and the nutrients go via the umbilical cord.
A developing mammal inside of the mother.
A developing chick nourishes itself inside the eggshell through the egg yolk. This is the chicks source of food.
I believe it is called an embryo
what is the source of nourishment for developing fish embryos?
An egg yolk is the part of an egg which serves as the food source for the developing embryo inside.
A mammal embryo is the developing baby inside the mother.
Gilbert's Potoroo is a small mammal which lives in Western Australia in a restricted habitat, with a restricted food source. It was believed to be extinct from the early 1900s, but its recent rediscovery has led to the development of a recovery plan.
A placental mammal.
A rabbit is a mammal, and as such it is an endotherm. He produces his own heat from the energy he gets from his food, and has no need of an extern source like the sun or a radiating lightbulb.