Crab

Crabs are available in almost every world, but are replaced by Diver Sharks in Shrouded worlds. They become available for purchase once you have 4 sharks and 4 rays. Their description is "Hire a crab to find things that sharks and rays overlook."

Career Path
Crabs have the option of becoming Planter Crabs after researching Kelp Horticulture. In most worlds this is the first available method for gathering kelp.

Laboratory Research
There are 3 upgrades that can be researched that are specific to only crabs, 1 generic upgrade that affects crab income, and 1 upgrade specific to all crustaceans. The research listed below is available in every world and has an effect on crabs and their jobs: {| class="article-table" ! scope="col" |Upgrade ! scope="col" |Description ! scope="col" |Result ! scope="col" |Cost

Sun Observation
We must determine what is with the weird glare on the surface of the water. Planter crab power x2
 * Planter crabs are twice as effective, and shrimp are four times as effective. Is a suns worth many fish? We can see a sun, but where is it really? And by what is it made of?

Unlocks Crab Biology
 * 5K Science

Far Explorations
Explore the vast reaches beyond the home ocean. The following research is available in every world besides Shrouded: {| class="article-table" ! scope="col" |Upgrade ! scope="col" |Description ! scope="col" |Result ! scope="col" |Cost
 * Crabs are four times as effective. Did you know oceans are actually even bigger than big? Remarkable!
 * Crab power x4
 * 8K Science 15K Fish
 * }

Kelp Horticulture
Determine what it takes to plant kelp all over the seabed. Maybe this is useful.
 * Crabs can become kelp farmers and grow a living carpet across the bottom of the sea.
 * Unlocks Gear up planter crab
 * 1K Science 2K Sand

Crab Biology
Crabs are a mystery. They keep to themselves and dig up crystals or put down plants. What is even up with that? What ARE crabs?? Crab power x4
 * Crabs and planter crabs are twice as effective. Crabs are alright but they are also sort of terrifying and weird. Good job they're on our side!

Planter crab power x2

Unlocks Form crab brood 500 Science

100 Kelp

Utility Carapace
The exoskeleton is good enough, but with some adjustments, perhaps coralglass can improve it. Crab power x4
 * Crabs, shrimp and lobsters, and their roles, are all four times as effective. A shell protects, and a shell interfaces.

Crab brood power x4

Planter crab power x4
 * 10B Science
 * }

Story
Warning: This section includes speculation, as canon answers don't yet exist. Dutiful, loyal crustaceans.

There isn't much known about the crabs, but they seem to be fairly simple creatures. Unlike shrimp and lobsters, they aren't advanced enough to have developed their own technology. They seem happy just farming and digging for crystals. A few of their kind are curious enough to investigate the teamwork of sharks and rays, leading to their employment in the first place. All indications are that they are hard workers who ask very little in return.

It's implied that crab broods are unusual, as mentioned in the log: "The crab brood is a rarely witnessed phenomenon, due to being some strange behaviour of crabs that have been driven to seek crystals for reasons only they understand." From this message it also seems as though digging for crystals isn't normal crab behavior either, but it's unclear how many crabs have really been observed by the narrator shark before the game began.

The crabs are concluded to be "sort of terrifying and weird", but are generally trusted by the sharks no matter how much their numbers grow.

Trivia
Aside from being used to purchase ray makers, the main purpose of kelp is to aqcuire sea apples which can then be studied to gain science. It isn't immediately obvious what sea apples are if you aren't already familiar with the term. If you pay attention to your log, you may notice that they're said to squirm. This is because 'sea apple' is the common name for a variety of sea cucumber, an invertebrate marine animal with leathery skin. They are filter feeders like clams and sponges, and while they aren't generally associated with kelp they have been known to eat plant-like microorganisms.