Which horseshoe crab species is this?

The body of the horseshoe crab can be divided into three parts: prosoma (carapace), opisthosoma (abdomen) and telson (tail). They leave three parallel traces on the mudflat when they are crawling on it.

The main difference between the Chinese horseshoe crab (Tachypleus tridentatus (TT)) and the mangrove horseshoe crab (Carcinoscorpius rotundicauda (CR)) is that TT has a triangular shape △ telson with spine while CR has an oval shape ○ telson and smooth.

Besides, TT has a row of hard spikes on the two sides of the opisthosoma, and there are three tooth-shaped spines protruding from the end of the abdomen (one in the middle above the tail and one on each of the left and right sides), so it is also known as the tri-spined horseshoe crab. CR, on the other hand, has only one spine in the middle.

Points to note during survey

When taking photos of horseshoe crabs from the wild, it is always better to provide an object as scale so that we could estimate the size of horseshoe crabs. You can make use of commonly seen everyday objects such as a coin or Octopus card as scale.

The mangrove horseshoe crab (Carcinoscorpius rotundicauda (CR))
The Chinese horseshoe crab (Tachypleus tridentatus (TT))

Respect our nature. Please do not harm or take away any wildlife in the countryside.

How to get GPS coordinates from Google Maps

For accurate information, it is important to know the exact location where the horseshoe crabs were found. Here is a guide on how to get latitude and longitude GPS coordinates using Google Maps.

For phone users,
1. Open the Google Maps app.
2. Go to the location for which you want the GPS coordinate.
3. Touch and hold the location of the map. You’ll see a red pin appear.
4. For iPhone user, tap Dropped pin at the bottom, you’ll see the coordinates; For Android user, you’ll see the coordinates in the search box at the top.

For computer users,
1. Open Google Maps in your browser.
2. Go to the location for which you want the GPS coordinate.
3. Right-click the location and select What’s here For computer users,
4. Find the GPS coordinates at the bottom of the screen

Sighting Report

To promote public awareness on horseshoe crabs’ conservation effort, citizens reporting the sighting of horseshoe crabs in Hong Kong with the following form will receive a unique souvenir!

  1. The submitted photos should include one showing the horseshoe crabs and peripheral environment for validation of location, and one close-up of the horseshoe crabs, with a scale bar, for species validation.
  2. The promotional period will end on 31 August 2020. The photos must be taken in 2020.
  3. User will receive a confirmation e-mail for the souvenir after our validation (NOT the thank you e-mail after sighting report submission). Please provide us your mailing address below as the souvenir will be mailed to you after the confirmation. 
  4. Giveaway is available on a first-come, first-served basis. The AFCD reserves the right of final decision.