Disclaimer: I'm no biologist. I just read a lot of papers.
NWSiaCB said:
It's a common dolphin with a bottlenose dolphin. They're different species.
Common dolphins (Delphinus spp.) can interbreed with bottlenoses (Tursiops truncatus) though, and the hybrids (both sexes) are at least partially fertile enough to backcross with bottlenoses.
Note that most of the dolphin hybrids (and that one wholphin mentioned by Rathrue, 'though technically speaking all dolphins are whales) involve bottlenoses. These guys have a pretty high sex drive, and are the ones infamous for beating up porpoises and being infanticidal rapists and making untoward advances toward humans.
On the flip side, bottlenoses also tend to be the most friendly with humans, and the ones that save humans in reported cases are also usually bottlenoses, so maybe they're just less concerned with the interspecies barrier...
Vaccine said:
Come to think of it... All dolphin species excluding Orcas can cross-breed like dogs? No? Or it isn't possible like mouse and rat?
Dogs are the same species. Same subspecies even, Canis lupus familiaris. The differing looks of the breeds are mostly because of human breeders selecting for specific traits (purebreds tend to be horribly inbred as a result); mongrels and crossbreeds tend to revert to a similar body type.
The different dolphin species don't regularly interbreed though, because they're, well, different species. They are significant barriers to forming viable animal hybrids (unlike plants), moreso for mammals, starting with habitat (different species don't regularly live together), activity (different active times), the shape of reproductive organs (can't fit) and reproductive practices (again, can't 'fit'), the sperm and ova themselves (spermatozoa need certain specific biochemical triggers to fuse with the egg coat), the genes themselves (different species usually have mismatched [even if the chromosome numbers are the same] chromosomes, so even if by some miracle you get a viable hybrid offspring that doesn't die as a fetus due to all the possible genetic defects, it usually winds up being sterile because the genes from its father's and mother's sides can't pair up properly during meiosis), and even the number of teeth (you get a viable hybrid, and it's even fertile somehow, but it has fucked-up dentistry because the father and mother have different numbers of teeth, so it can't survive in the wild without handfeeding).
Bottlenoses are a notable exception because they're a promiscuous species that regularly interacts with other species (like D&D humans, heh), and cetecean DNA are somehow oddly compatible with each other (the hybrids tend to be extremely intermediate in traits [especially the number of teeth] between both parents).