talking points for nature guides
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Phylum Arthropoda > Subphylum Crustacea > Class Malacostraca > Order Decapoda > Brachyurans > Family Ocypodidae > Genus Uca
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For nature guides: introducing fiddler crabs
updated Apr 2020

Don't step on the fiddler crab!
Fiddler crabs make a good 'first station' to sensitise visitors to the fact that every inch of the shore is alive.

The Big Useless Claw Story

It is important to get the sequence right or it will NOT make sense to the visitors.

Step 1: "Stay very still and you will see some interesting animals on the sand. They are very small and very sensitive to your footsteps. If you wave your arms around they will think you are a bird and will hide. Pretend you are a tree and they will come out." This will make visitors get used to not stomping around. To be still and look carefully for small things that will only come out when there is no disturbance.

Step 2: If it's taking a while for the crabs to come out "While we wait, let's look around us and I'll tell you about some of the special ecosystems we can see around us. Meanwhile DON'T MOVE!"

Step 3: Once crabs are active, get visitors to realise the one big claw, e.g., "How many claws does the crab have?" Eventually someone will say "One".

Step 4: Give information to visitors that the big claw is useless: "Actually it has two claws. The big claw is so big that it misses the mouth. It has a much tinier claw that it uses to feed itself. Can you see one feeding?"

Step 5: Give information that this situation is only found in the male crabs: "Only the male crabs have one big useless claw. The females have two small claws so they can feed twice as fast."

Step 6: "Why do you think the males have one big useless claw?" Usual guesses: to find food, for fighting, for defence from predators. Explain briefly and clearly why these are not the case. Goad them with "Why do all boys have big useless things? Like sports cars?" Eventually someone, usually a girl or a small child, will say "To attract girls"

Step 7: If you are lucky and the visitors have been very very still, you can say "These tiny crabs are all over the place. You can see some near your feet too! See!!! Every inch of of the shore is alive with creatures. Some of them are small and buried in the sand. Every step we take on will most definitely squash something."

"We have designated a trail on the shore. It is a death zone. Just like any nature park in Singapore. At Sungei Buloh or Bukit Timah, we don't walk anywhere we want to but have to stick to a trail. Otherwise, a larger and larger area will become 'botak' (bald) as footsteps kill off small plants and animals.

"To minimise this death zone, please stay close to me and try to stay in a single file."

If you are not the first group "Follow the trail made by the group in front. Then you don't kill things that they haven't already killed."

Handling tips

Finding fiddlers: These crabs are usually found near mangroves and seagrasses. They are active during daylight.

Do NOT pick up fiddlers
Visitors will do as we do and not as we say. In any case, if we catch them and put them down far away from their burrow, they will be stressed and may not be able to find protection and then die.

Do NOT dig up fiddlers either. This is destructive to the habitat, and encourages visitors to dig up everything they want to see. Instead, encourage them to be patient and wait for animals to come out and go about their normal business.
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