By Sea

Crab
Exoskeleton. Crabs are scavengers to the bottom of the sea and along shores and rocks. They use their pinchers to pick up the debris and waste and bring it to their mouths. Other crabs like the fiddler crab have one large pincher they use as a means to attract a mate by waving it. Crabs also raise and open their pinchers as a warning gesture to ward off predators. If they get a pinch of you they'll hang on even if they're detached from the offending pincher. Crabs loose their legs fairly easily anyway though and if they live to tell the tale their legs and pinchers will grow back. If your dream consists of being pinched by a crab who isn't letting go, it can more denote a playful side of yourself.

Fish
Fish can represent the abundance of the sea. In Christianity the fish were used as a symbol like the crucifix after the story of how Christ turns a basket of fish and bread into enough to feed everyone. The concept of sharing. They also represent the astrological Pices, which literally means "the fishes".

In some religions the oil or what looks like a white silken pouch of fat near the backbone in certain fish was used for sacred ceremonies, candles and sacrifices. Fish eggs or caviar is considered a fashionable delicacy and in dreams could have something to do with your sense of prestige or fine qualities.

Fish in dreams could perhaps be seen as creative notions coming into realizations. Often the philosophy behind going fishing is that even if one might not catch anything all day long, the time would still be enjoyed.

Fishy. Fish out of water. Gone fishing. Fishes in the deep blue sea. Other fish to fry.

Hermit crab
Mysterious discoveries. Revealing the hidden. Child self. Hermit crabs don't make their own shells but live in the ones sea snails have discarded. The hermit crab makes this his protective home until he out grows it, then goes in search of a bigger shell to move into. They're bottom feeding scavengers who can go by land or sea and have an art for hiding and camouflage.

Hermit crabs can also be seen as very shy and timid, they 'blossom' out very slow and cautiously but at the first hint of any trouble real or imagined they shoot back in as quick as a blink. Their largest symbolism can be of withdrawal which they do by scooting themselves as deep into their shells as possible to keep predators at bay. They could also symbolize of shelling away from the rest of the world as they keep their shells and carry them around with them where ever they go. Which one are you doing? Hermit crab might be encouraging you to "come out and play".

Octopus/Squid
Eight legs

Shark
The shark is a virtual Teranasaurus Rex of the sea. They are specialized for the hunting and bringing down of prey and have a very keen sense of smell. They use a system of 'bumping' into something to check out things they aren't sure of but there can be cases a bite isn't far behind as they also use a first bite to determine the taste of a potential meal. This is why most humans will experience a shark bite and live to tell the tale. Sharks mostly mistake humans for seals, but apparently we don't taste like one.

Sharks are also capable of using the water currents to literally leap out of the water after a fleeing seal. They are still being studied but it appears that most sharks habitually come towards inland at the high tides and move further out to sea in the low tides.

They are also known for eating in large frenzies and will stuff themselves such as on a whale carcass until they have become completely gorged and euphoric. When sharks mate the male has to be big and strong enough to roll the female over on her belly up.

In dreams it is possible for shark to represent 'bumping' or 'pushing' into other plains of awareness and travel. They can teach how to relax fear or even how to use fear. It wouldn't be a great idea to harm your dream shark. They are a symbol of strength, speed, proficiency, distances and warding.

I've noticed out on the road with highway patrol how the police literally drive like the stealth of a shark.

Starfish
Five points

Stingray
Stingray's have a rather alien appearance, gliding through the waters on 'wings'. Just below their tails is a long 'stinger' they use to ward of predators. Some are very poisonous but generally stingray's are passive bottom feeders who also make use of camouflage such as digging themselves into the sand to blend in with the invironment.