We scuba divers can't talk underwater, yet communication is key for a number of reasons, including safety. But a good dive buddy also gives his or her fellow divers a heads-up when an interesting ocean creature is nearby. So how do you alert your dive group when a shark is finning by, a crab is hidden under a ledge or a tiny nudibranch is barely visible to the human eye? We've put together 23 scuba diving hand signals for identifying marine life — in the video above, or GIFs below — so that you and your buddies never miss out on spotting some of the ocean's most beloved creatures.

SEE MORE: Basic Scuba Hand Signals Every Diver Should Know

Angelfish

Angelfish are a common sight — especially for divers who frequent popular Pacific and Caribbean and western Atlantic dive hot spots — but it's still a treat when you see them on a flourishing reef. Take your finger to make a circular motion around your head to mimic an angel's halo.

Boxfish

The hand signal for a boxfish is pretty self-explanatory. Take your thumbs and index fingers to form a box, indicating that you've spotted a fish that, when overstimulated, releases a toxin lethal to some marine life.

Clown Anemonefish

Did you find Nemo? Let your buddy know by making a circular shape with your hand and putting it on your nose — in imitation of a clown's big red nose.

Crab

Crabs are often found hiding under ledges or in the nooks and crannies of a reef. Pinch the fingers of your hands together like the pincers of a crab for this hand signal.

Barracuda

With elongated bodies and sharp teeth, barracuda are easy to spot cruising around the ocean. Use your fingers to make "stripes" on your arm — to emulate a barracuda's distinctive markings — to point one out.

Dolphin

If you spot a dolphin, you better react quickly! These fascinating marine mammals don't often stick around for long. Use your index finger — or your hand — and undulate it up and down to imitate how a dolphin uses its powerful tail flukes to propel itself through the water.

Fire Coral

Your buddies will thank you for alerting them to the presence of nearby fire coral, a hydrocoral capable of causing divers great pain when directly contacted. Note the two-part signal: Imitate the "fingers" of coral, followed by pantomining how you'd use your thumb to start the flame on a handheld cigarette lighter. If your buddy looks like he's asking you for a light underwater, diver beware!

Garden Eel

It's not hard to spot a group of garden eels — they can be seen on sandy bottoms with their heads popping out of their burrows. Emulate this behavior with your finger to perform this signal.

Grouper

Groupers — especially the Goliath grouper — are known for their big, fat lips and even bigger mouths. Bend your arms and move them up and down like a large grouper mouth. You can also indicate that there's a large fish nearby by using your hands to gesture something huge.

Jellyfish

Take your hand and float it up like a jellyfish — with your fingers trailing like a jelly's tentacles — to let your dive buddy know there's one nearby.

Lionfish

A nuisance in the Caribbean and western Atlantic and native species in the Indo-Pacific, the lionfish is an impressive sight. Interlock your hands and move your fingers back and forth to demonstrate the lionfish's mane-like fins.

Lobster

Like crabs, lobsters are often found hiding under ledges. Take your fingers and point them like antennae if one is nearby.

Manta Ray

This one is easy. If you see nearby divers waving their arms like they're gigantic flying birds, a special encounter is upcoming.

Moray Eel

Often found swimming about reefs in a snake-like motion, moray eels are a treat to spot on a dive. They are also commonly seen poking out of crevices, opening and closing their mouths to flush oxygen over their gills. Use the same hand signal you use to imitate someone who talks too much to mimic this behavior.

Napoleon Wrasse

Also known as humphead wrasse, this strange-looking fish is a diver favorite. History buffs know just where this hand signal comes from. (Hint: Google Napoleon.)

Nudibranch

It takes a sharp eye to spot one of these macro critters — a favorite for divers. Take your fingers and wave them like a nudi's rhinophores when you see one.

Octopus

Wiggle your fingers like a bunch of tentacles to signal an octopus is nearby.

Pufferfish

As long as you don't harass this fish, you won't see it inflated. But you emulate an inflating sphere with your hands to show that one is close.

Seahorse

We had some fun with this one. Get your giddy-up on to signal that you've seen one of these beloved marine creatures.

Shark

Sharks might be divers' favorite animal to see on a dive. If you do spot a nearby shark, take your hand and place it on your head like a fin.

Stingray

Stingrays can camouflage themselves pretty well. Poke a stinger out from your other flat hand to signal to your buddy that you've seen one.

Turtle

Dude. It's not hard to signal that you've spotted a sea turtle. Bring your hands together and make a circular motion with your thumbs.

Whale

Whale encounters are special. Make sure no one in your group misses it by making a breaching motion with your hand.