Horseshoe Crab (Limulus polyphemus)
Salem Sound Coastwatch is asking volunteers to help us learn more about horseshoe crabs in Salem Sound, particularly if they are spawning.
We are most likely to see horseshoe crabs spawning around
FULL or NEW moon at high tide. They can be found on
protected sandy beaches. Look for them on beaches where there is not a lot of wave action, such as those found in estuaries.
SSCW is also looking for historical photos of spawning beaches throughout the last century. Of special interest are images that show horseshoe crab spawning activity, but photos of typical spawning beaches are also of interest to us. Or let us know if you have a story to tell about horseshoe crabs.
A group of burrowing horseshoe crabs along the shore.
Photo courtesy of Division of Marine Fisheries (DMF).
Tips for spotting horseshoe crab spawning habitat - courtesy of DMF.
- When horseshoe crabs spawn, the female will burrow into the sand to lay eggs. One or more male crabs will gather around her.
- Spawning crabs should not be disturbed.
- Please do not report coupled crabs (a female with a male attached) that are free swimming and not burrowing. Male crabs will attach to the female crab days or weeks before spawning begins.
- Please note the location including the name of the beach, nearby street or other landmark if you spot horseshoe crabs spawning.
Horseshoe Crab Facts
- Horseshoe crabs are prehistoric creatures that have roamed the earth’s coastlines for 350 million years.
- The local species, known as Llimulus polyphemus, is found from Maine to the Yucatan Peninsula in Mexico, with the highest concentrations in Delaware Bay.
An extract from horseshoe crab blood is used worldwide to ensure the safety of many medical products injected or implanted into humans.
- Horseshoe crabs are used as bait in the eel and channeled whelk fisheries.
- Horseshoe crabs are important in estuarine ecosystems. As they plow through the sand feeding, they stir up nutrients, worms, and other organisms making them available to small fish and invertebrates.
- They are harmless to humans. Their spiky tails are used primarily as leverage to turn over if they get flipped upside down.
- Additional information on Horseshoe Crabs