Special occasions have their own logic. You might never drink champagne ordinarily, but it's almost obligatory for a big celebration. So is splashing out on an expensive meal, like a prime rib or some lobster or better yet, both. Adding a lobster tail to the meal is an easy upgrade, and you can find lobster tails relatively easily. Depending on the store and where you live, the tails may come from a Maine lobster or a rock lobster. Rock lobsters aren't as good, so it's worth knowing how to spot the differences.
Here's the Science
Maine lobster tails and rock lobster tails come from entirely different species. The Maine lobster is known to marine biologists as Homarus americanus, the American lobster, while rock lobsters belong to dozens of different species that are all closely related to each other but not so much to the Maine lobster. If you're a biology geek, you'll want to know that they belong to a whole other genus, the Palinuridae. The good news is that all rock lobsters have a lot in common, so regardless of where they're from, you'll be able to identify them pretty easily.
Recognize Rock Lobster Tails
There are several ways to recognize a rock lobster tail when you see it. One of the easiest is to turn it upside down and count the little legs or "swimmerets." If you see five pairs, you've got a rock lobster. Rock lobsters are also known as spiny lobsters, and that's another clue. If you see formidable-looking spikes running along the edge of the tail, that's a rock lobster. Rock lobsters tend to a wider range of colors than the Maine kind as well, so you'll see a lot of relatively pale yellows and browns as opposed to the Maine lobster's usual dark green-brown with hints of red. Rock lobsters from some warm-water regions also have a distinctive eyelike spot on either side of the tail.
Recognize Maine Lobster Tails
Maine lobster tails are rarer, because the American lobster has something rock lobsters don't: marketable claws. The meat in the claw is tenderer and choicer than the tail meat, and whole lobsters make for a nicer presentation, so producers usually only separate the tails when the claws are deformed or missing. Maine lobster tails only have four sets of legs on the underside, and they don't have visible spines or the spot that marks a warm-water lobster tail.
Identify by Price
You can usually tell the difference between Maine and rock lobster tails by their price too. Maine lobster tails are in relatively short supply, and they're generally considered the best, so they command a premium price. Lobster tails sold at a special door-crasher price at your local supermarket or seafood merchant – or as a surprisingly inexpensive add-on at a restaurant – are probably rock lobster. There are differences even among rock lobsters, though. A good rule is that the cooler the water, the tastier the lobster. The cold waters of Maine and Atlantic Canada produce exceptionally good lobster, but you can also find cold-water rock lobster tails from Southern Hemisphere countries like South Africa, Australia and New Zealand. They aren't quite the same as a Maine lobster, but they're definitely sweeter and finer than warm-water tails.
Take Your Pick
There's a time and a place for each of these products. When you're celebrating a special occasion and you're willing to pay for the best, that's certainly a Maine lobster. Rock lobsters have their advantages too, though. They're usually meatier than Maine lobster tails, so you get more to enjoy. Warm-water lobster tails aren't as tasty or as fine-textured, but you'll be able to enjoy them more often because of their low price. Cold-water rock lobster is a fine product in its own right, and if you're using it as an ingredient rather than serving it whole, you'll see very little difference between a rock lobster and a Maine lobster in the finished dish.