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7 Facts About the Awesome Galapagos Sally Lightfoot Crab

Are you looking for some great facts about the Galapagos sally lightfoot crab? You’ve got them here, enjoy!

galapagos sally lightfoot crab

Sally… What Now?

The strange name is quite fitting for these funny little crustaceans. Sally lightfoot crabs are very entertaining.

Why would someone sit around and watch crabs? If the shoe fits… I love these crabs, I find them quite amusing. They seem to look at people with a classic “I’m better than you” cockiness.

Sally Lightfoot Crabs by the Numbers

  • Latin name: Grapsus grapsus
  • Length: The ‘carapace’ (fancy word for ‘width of shell’) is 3-5 inches (8-12 cm) across.
  • Weight: Unknown, but likely around half a pound. If you know the weight of the sally lightfoot crab, please tell me in the comments and help me improve this post.
  • Color: From a dark red to bright orange to nearly brown. They also have an underside that can be light yellow, white, or blue – or even a combo of all three!
  • Cool feature: Adults seem to have a sore lack of camouflage. It would seem they don’t really need camouflage because they can out-maneuver almost anything.

The Sally lightfoot crab is sometimes called the red rock crab.

sally lightfoot

7 Facts About the Awesome Galapagos Sally Lightfoot Crab

1. That’s my Name, Don’t Wear it Out!

The origin of the sally lightfoot crab’s name is still debated. Some people say that the sally lightfoot crab was named after a Caribbean dancer.

The crab certainly has earned its name! The sally lightfoot crab can run very fast, leap, jump, and seemingly fly to avoid predators.

It could also be that the sally lightfoot crab is simply light on its feet – and named Sally.

2. Please Sir, May I Have Some More?

Sally lightfoot crabs and Galapagos marine iguanas have an “absolutely-disgusting-but-mutually-beneficial” relationship.

They have formed what is known as a symbiosis. This means that each participant in the relationship gets something of value (kinda like divorce).

In this case, the sally lightfoot crab eats skin parasites and dead skin off of the marine iguanas. So the iguana gets a bath (sort of) and the crab gets a delicious meal of disgusting dead stuff nobody else wants.


3. Tiptoe…

Because of their pointed legs (they don’t really have feet), Galapagos sally lightfoot crabs can get an amazing hold on the lava rocks.

They will stick the tips of their legs in the tiny holes in the lava and hold on tight. This way, they can avoid falling off, even when powerful waves wash over them.

sally lightfoot crab facts

4. Camo Crabs?

Baby sally lightfoot crabs are black, or very dark brown with small white and red spots. Why? The lava all over the Galapagos islands is black, so the babies blend in better.

When we were in the Galapagos, we saw both young and old sally lightfoot crabs. The babies were so tiny! If my memory serves me, I remember some being about as big as a dime. It was really neat to see how well the blend into the lava.

5. Living on the Edge!

Why do sally lightfoot crabs change color as they get older? Logic seems to suggest that they would stay black so as to avoid certain death. I mean really!

With the bright red, yellow, and blue, it’s basically an “attack here” target.

As they get older, they get faster, smarter and more devilish. What do I mean by devilish? It seems like their only goal is to drive us crazy! Check out what John Steinbeck said about how these awesome little stinkers seem to avoid danger:

“They seem to be able to run in any of four directions; but more than this, perhaps because of their rapid reaction time, they appear to read the mind of their hunter. They escape the long-handled net, anticipating from what direction it is coming. If you walk slowly, they move slowly ahead of you in droves. If you hurry, they hurry. When you plunge at them, they seem to disappear in a puff of blue smoke—at any rate, they disappear. It is impossible to creep up on them.galapagos crab

Man reacts peculiarly but consistently in his relationship with Sally Lightfoot. His tendency eventually is to scream curses, to hurl himself at them, and to come up foaming with rage and bruised all over his chest. Thus, Tiny, leaping forward, slipped and fell and hurt his arm. He never forgot nor forgave his enemy. From then on he attacked Lightfoots by every foul means he could contrive (and a training in Monterey street fighting has equipped him well for this kind of battle). He hurled rocks at them; he smashed at them with boards; and he even considered poisoning them. Eventually we did catch a few Sallys, but we think they were the halt and the blind, the simpletons of their species. With reasonably well-balanced and non-neurotic Lightfoots we stood no chance.” – via Wikipedia, Graspus Graspus entry.

I know it’s a huge quote, but I just love the way this guy writes! “they disappear in a puff of blue smoke!

In other words, they are so fast (and annoying) that they have no need for camouflage.

6. How do Sally Lightfoot Crabs Change Colors?

This is pretty amazing. The crabs change colors by molting their shells. I had heard before that crabs could do this, but it’s still pretty awesome!

When sally lightfoot crabs hatch, they are black with small red spots. Each time they change their shell, the spots get bigger until the crab is eventually all red! Isn’t that cool?

7. I’m Walking on Sunshine!!!

Water. I’m walking on WATER. Who walks on sunshine anyway? (I do love the song, but hey; I’ve got to rant about something people!)

While I don’t have a source to quote you or a video to show you, I clearly remember watching sally lightfoot crabs “walk on water.”

When they get frightened, sally lightfoot crabs will launch themselves onto the water, and then hop/skitter/jump across it. It was totally awesome to watch! JEL-ous – why can’t I walk on water??

sally lightfoot crab galapagos

Edgy Tip-toe Dancing Rainbows!

Those are my 7 wacky facts about the Galapagos sally lightfoot crab, I hope you enjoyed them!

Please tell me if I left something out or if something is unclear. I love to hear your feedback in the comments. Keep helping me improve!

Cruising The Galapagos Islands – Journey of a Lifetime | WorldWideAdventurers

Monday 14th of November 2022

[…] In contrast to the Black Marine Iguanas is the bright Red Sally Lightfoot Crabs.  Would you believe the crabs and iguanas live in total harmony on the seashore –  in fact they have a very interesting relationship according to Drew at […]


Friday 4th of October 2019

Oops! My name is Karen, not Emily

Emily Siderits

Friday 4th of October 2019

Hey winderul blog!

I am doing a project on puffin birds for sckhool. We should collabb on an article!

Thanks! Peace Love Karen.

Drew Haines

Thursday 31st of October 2019

Hi Karen, thanks so much! Hope you get a good mark on your puffin project :)

Naomi Crosby

Sunday 7th of April 2019

I have also heard that when they moult they leave their stomachs behind with the old shell. This explains how they manage to eat absolutely anything - they just leave their stomach ache behind. (and being able to eat anything is the reason they are so successful).

Drew Haines

Sunday 7th of April 2019

Sounds fascinating!


Sunday 10th of February 2019

: )

Drew Haines

Tuesday 12th of February 2019