ALOT. All mammals except the platypus.
Birds develop internally, which means inside the creatures body.
exernally
Most fish eggs develop outside of the body. There are however around 3% of all fish which fertilize internally.
GiraffesElephantsRhinosPenguinsOrangutansWhalesSnakesTurtlesChickenMosquito
Actually,the chicken,dog,cat,turtle,and the mosquito fertilize internally.
example of develop inside the body of animals
There is no external water source to carry the sperm
Animals that do not develop in a placenta will develop outside of the uterus rather than in. Kangaroos and Koalas use pouches to develop their young.
No, actually there is a third choice. They are ovoviviparous as their eggs develop internally and they bear live young.
There is a very simple sequence in which most animals develop. Most animals are born, mature, reproduce, and then die.
There are a great number of characteristics that animals posses that can help them reproduce. The ability to fertilize internally is one of them.
Plants could clean and heal the body. Plants can also clean animals internally, when taken orally.