This world is really big and full of wonders. No matter what kind of plants, animals, or microorganisms they are, there are many types. For example, take the types of fish, there are hundreds of them. But as for the types of fish, the most common ones we see in life are eels, squid, grass carp, crucian carp, carp, etc. The fish meat is very tender and delicious. We can all distinguish common fish, but we may not be able to distinguish uncommon ones. For example, we can’t tell the difference between squid and cuttlefish. Do they belong to the same species? The answer is that squid and cuttlefish are not the same species.

Squids and cuttlefish are both molluscs, and they look very similar. For example, squid and cuttlefish have long whiskers. For people who rarely see squid and cuttlefish, it can be difficult to tell the difference between the two. So are they the same species? The answer is that they are not the same species. The word species appears in Origin of Species, which refers to the ability of animals to mate to produce offspring that are reproductively isolated from other similar groups. Just like squid and cuttlefish, although they look very similar, they are reproductively isolated. For example, the offspring of a horse and a donkey, a mule, is incapable of producing offspring.

To determine whether two similar-looking animals belong to the same species, the key is to see whether the offspring born after the two animals mate are fertile. If there is, it means they belong to the same species; if they don't, they don't belong to the same species.

Although squid and cuttlefish look very similar, it is easy to confuse their species. But the shape of the squid, that is, its body is more slender than the cuttlefish, and its tail is also pointed and conical. The body of a squid is wider. Sometimes you can see seafood-eating anchors stuffing rice into squid’s stomachs on Kuaishou. Moreover, squid and cuttlefish belong to different families. Squid belongs to the order Cephalopod, order Sepia, and family Sepia, while squid belongs to order Cephalopoda, order Decabrachia, and calamari. So they are not the same species.