The Location: The Laurence Harbor Waterfront Park ends
here at the mouth of Marquis Creek on Seidler Beach. It is a
favorite spot for fishermen as well as bird watchers. One day the
boardwalk may continue as far as Whale Creek to the south but for
now, this nearly forgotten little strip of beach is a haven to
various seabirds & a breeding ground for the original Ancient
Mariner - the Limulus Polyphemus, aka the Atlantic Horseshoe Crab.
A few caches have graced this location & hopefully this one
will survive a little longer.
Physiology: The Horseshoe Crab is a
living fossil. Nearly identical forms have been found dating
dating back to the Triassic period some 230 million years
past. They are not actually crabs, but are more closely
related to spiders. They are unique on this planet in having a
pair of compound eyes to go along with at least 8 other
light/motion sensing "eyes" scattered around their shell, tail
& body. Each eye or pair of eyes serves a single purpose:
to find a mate, move in a straight line, or detect food. A few
can even see ultraviolet light like a cat! There are three
divisions to their bodies: the prosoma (or cephalothorax), the
opisthosoma (or abdomen), & the telson (also known as the
tail). The prosoma is made up of the main shell, legs &
mouth. The first two legs are used for stuffing food into the
mouth while the others are mostly used for getting around.
Male Horseshoes will have small pincers on their second set of
legs that they use to hold on to their sweeties in the Spring
time. Like a starfish, they can regenerate these limbs if lost
to predators. Their gills & swimming muscles make up the
majority of the opisthosoma. The tail is just that & not
actually used for a weapon. They use it steady themselves
while swimming & for righting themselves if they get
flipped over. Horseshoe Crabs are covered in up to 100,000
microscopic cuticular peg & pit sensillum allowing them to
feel (and taste!) with every part of their body - even the
shell. One of the reasons they've survived so long is their
incredible blue blood. The blood is blue because it is
copper-based rather than iron-based like ours. Though
horseshoes don't have an immune system like mammals, they have
agents within their blood that cause instant clotting &
binding when presented with toxins. It is so effective that
their blood is used for testing medicines for the dangerous
endotoxins that can survive even steam-sterilization. The last
time you received a shot at the doctor's office, it's likely
that medicine was tested with the blood of the horseshoe
crab!
Growing Up in the Neighborhood: Mature horseshoes (9 to
11 years old) will pick a sandy area with low wave action like our
bay here to have their kids. They lay the eggs (as many as 4000 at
a time!) in the damp sand between high & low tide.
It will take on the average only two weeks before a baby
horseshoe crab hatches into recognizable form. It will spend
the next week swimming out into the bay but only making it a
few hundred feet. They grow very slowly & will be only a
1/2" long after the first year. They can only grow by molting,
or shedding their old shells & growing into a new one.
Their first two summers will be spent on the shallow
sholewater areas around they bay before moving out to the
intertidal sand flats. Horseshoes will molt several times a
year before slowing to once a year after 3 or 4 years. All of
the horseshoes you see here will be adults. In the fall
they'll return to the sand flats or swim out to the
continental shelf to enjoy the gulf stream. Horseshoe crabs
can live to around 20 years old in the wild.
Just Flip'em! Horseshoe Crabs are still listed as a
threatened species & are very important to coastal marine life.
They do a good job cleaning up the floor of the bay eating algae,
worms & small clams & oysters. In turn, their eggs feed the
gulls, sandpipers & plovers during their migration. Horseshoes
are also often a mobile home to oysters, barnacles, worms, snails,
starfish & many other types of sea life. These hichhikers are
not hurting the horseshoe, but actually protecting it from
predators. So, when you encounter a horseshoe crab upside down on
the shore,
Just Flip'Em
over! Don't use the tail - though it looks dangerous, it's
actually sensitive & you could hurt the horseshoe. Their
claws are soft & they don't even have teeth so they wont do
you any harm.
This cache is certified
Central
Jersey!
