Tag Archive: crabs

In Search of Horseshoe Crabs

In Search of Horseshoe Crabs

Back in the spring, I wrote an article about the natural history of this ancient animal. However, Florida Fish and Wildlife Conservation Commission (FWC) is interested in the status of horseshoe crabs and they need to know locations where they are breeding – and Florida Sea Grant is trying to help.

Horseshoe crabs breeding on the beach.
Photo: Florida Sea Grant

If you are not familiar with the horseshoe crab, it is a bizarre looking creature. At first glance, you might mistake it for a stingray.  It has the same basic shape and a long spine for a tail.  But further observation you would realize it is not a stingray at all.

 

So then… What is it?

 

When you find one, most are not comfortable with the idea of picking it up to look closer. The spine is probably dangerous and there are numerous smaller spines on the body.  Actually, the long spine in the tail region is not dangerous.  It is called a telson and is most often used by the animal to push through the environment when needed, as well as righting itself when upside down.  It is on a ball-and-socket joint and if you pick them up, they will swing it around – albeit slowly – but it is of no danger.  Note though, do not pick them up by the telson – this can damage them.

 

If you do try to pick them up with your hands on their sides, you will find they are well armored and have numerous clawed legs on the bottom side. At first, you are thinking it is a crab, and the claws are going to pinch, but again we would be mistaken.  The claws are quite harmless – they even tickle when handled.  I have held them to allow kids to place their hands in there to feel this.  However, when held they will bend their abdomen between 90° and 120°, as if attempting to roll into a ball – which they cannot.  At this point, they become difficult to hold.  Your hands feel they are in the way and the small spines on the side of the abdomen begin to pierce your skin.  So, you flip it on its back.  It begins to try a 90° bend in the other direction and begins to swing the telson around.  This is probably the most comfortable position for you to hold – but I am not sure what the crab thinks about it.

 

So, what do you have?

 

Well, you can see why they call it a crab. It has clawed legs and a hard shell.  The body is very segmented.  You can also see why it is called a “horseshoe”.  But actually, it is not a crab.

 

Crabs are crustaceans. Crustaceans have two body segments – a head and abdomen, no middle thorax as found on insects.  This is the case with the horse crab as well.

 

Crustaceans have 10-segmented legs, though the claw (cheliped) and swimming paddles (swimmerets) of the blue crab count as “segmented legs”. Horseshoe crabs have 10 as well – seems this IS a crab – but wait…

 

Crustaceans have two sets of antenna – two short ones and two long – horseshoe crabs do not have any antenna. Traditionally biologists have divided arthropods into two subphyla – those with antenna and those without – so the horseshoe crab is not a crab.  It is actually more closely related to spiders, ticks, and scorpions.

Blue crabs are one of the few crabs with swimming appendages.
Photo: Molly O’Connor

It is an ancient animal, fossil horseshoe crabs in this form date back over 440 million years – out dating the dinosaurs. There are four different species of today and there probably were more species in the past.  Their range extends from the tropics and temperate coastlines of the planet.  Today three of the remaining four species live in Southeast Asia.  The fourth, Limulus polyphemus, lives along the eastern and Gulf coast of the United States.

 

Unfortunately, this neat and ancient creature is becoming rare in some parts of its range. There is a commercial harvest for them.  Their blood is actually blue and contains properties beneficially in medicine.  Smaller ones are used as bait in the eel fishery, and there is always the classic loss of habitat.  These are estuarine creatures and are often found in seagrass and muddy bottom habitats where they forage on bottom dwelling (benthic) animals.

 

FWC is interested in where horseshoe crabs still breed in our state. Some Sea Grant Agents in the panhandle are assisting by working with locals to report sightings.  Sea Grant also has a citizen scientist tagging program to help assess their status.  Horseshoe crabs typically breed in the spring and fall during the new and full moons.  On those days, they are most likely to lay their eggs along the shoreline during the high tide.  This month the full moon is October 5 and the new moon is October 19.  We ask locals who live along the coast to search for breeding pairs on October 4-6 and October 18-20 during high tides.  If you find breeding pairs, or better yet, animals along the beach laying eggs – please contact your local Sea Grant Agent.  We will conduct these surveys in the spring and fall of 2018 and post best search dates at that time.

 

For more information on the biology of this animal read http://escambia.ifas.ufl.edu/marine/2017/04/10/our-ancient-mariner-the-horseshoe-crab/.

 

 

References

 

Barnes, R.D. 1980. Invertebrate Zoology. Saunders College Publishing. Philadelphia PA. pp 1089.

 

Florida Fish and Wildlife Conservation Commission. Facts About Horseshoe Crabs https://www.sciencedaily.com/releases/2008/02/080207135801.htm

 

Oldest Horseshoe Crab Fossil Found, 445 Million Years Old https://www.sciencedaily.com/releases/2008/02/080207135801.htm

PG

Author: Rick O’Connor – roc1@ufl.edu

Sea Grant Extension Agent in Escambia County

Rick O’Connor

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/10/06/in-search-of-horseshoe-crabs/

Horseshoe Crabs; the Ancient Mariner

Horseshoe Crabs; the Ancient Mariner

Growing up in the Pensacola area, I do not remember seeing many horseshoe crabs around here, but I do remember them.  What I actually remember was how common they were further east in the Panama City and St. Joe area.  These animals are big fans of grass beds, as are sea urchins and scallops, and all are uncommon in our area now. However, there have been local sightings in recent years, so they may be returning.

Horseshoe crabs breeding on the beach.
Photo: Florida Sea Grant

Horseshoe crabs are actually not crabs at all but members of a group of arthropods called chelicerates, which include spiders, mites, and scorpions.  They differ from crabs in the absence of antenna, in which the crabs have two pairs. Their “horseshoe” shaped body is a body design to plow through the sand and mud searching for food.  They are scavengers and feed on mollusk, worms, and other invertebrates – even algae at times.  They do not have the large claws that blue crabs have, so they grab small bits of food where they can.  Horseshoe crabs do possess a crop and gizzard and have tooth-like structures within the gizzard to grind their food.  When digesting, the flesh is swallowed and the shell is regurgitated.  The large spine near at the end of their bodies makes them appear similar to stingrays, which they are often confused, but the spine is actually a telson and non venomous.  It is used to right itself when flipped and to push themselves in a forward direction.

 

They like shallow water and grassbeds are prime habitat for them. Breeding season is in the spring and early summer.  During the full and new moons, both the large females and smaller males approach sandy beaches in protected areas of the bay.  During the evening, they will begin to emerge into the intertidal zone where the female digs a depression and lays her eggs.  The males, usually riding her back attached by a special hook, will then fertilized the eggs before they are buried.  There may be more than one male trying to court the female (known as satellite males) and the numbers of horseshoe crabs on the beaches can be amazing.

 

Shorebirds, fish, and crabs will feed on the eggs and the young. Sea turtles are known to consume adults.  Being members of the phylum Arthropoda, they will have to molt their exoskeletons as they grow.  Many people will find these thin, tan-colored, molts along the shoreline.

 

There is a fishery for them in some parts of the southeast. They are collected for their blood, which is used in many medical processes needed for surgery and injections, and as bait for eels.  The decline of these animals has been problematic for some species of migratory birds, who feed on their eggs during their migration.  The horseshoe crab is also one of those rare animals that have been around longer than the dinosaurs.  It would be sad to lose this animal on “our watch”.  FWC is interested in where they are nesting.  If you are out walking the beaches of the Florida Panhandle and encounter one of them, please contact the Sea Grant Agent at your county extension office; we are particularly interested in where they may be nesting.  FWC has a website where sightings can be logged, http://www.myfwc.com/research/saltwater/crustaceans/horseshoe-crabs/documenting-beaches/.

 

The full and new moon cycles for spring and summer (2017) are:

 

Full Moon                                                                   New Moon

Apr 10                                                                         Apr 26

May 10                                                                        May 25

Jun 9                                                                            Jun 23

Jul 8                                                                            Jul 23

 

They could nest a few days before or after. We hope you get to see one, they are pretty cool!

PG

Author: Rick O’Connor – roc1@ufl.edu

Sea Grant Extension Agent in Escambia County

Rick O’Connor

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2017/04/15/horseshoe-crabs-the-ancient-mariner/

National Seafood Month – Blue Crabs

National Seafood Month – Blue Crabs

Well… we have talked about the “big two”… snapper and shrimp, but there are other popular fin and shellfish harvested from the Gulf of Mexico.  This week we look at my personal favorite… blue crab.

 

Probably like many of you out there, the very first sea creature I ever caught was a blue crab.  It was with one of those classic basket traps where you baited it, lowered to the bottom where you could see, waited until a crab came for the bait, and pulled her in… GREAT fun.  My parents cooked the crab, saved the shell and dated it.  It sat on the cabinet above our breakfast bar for years.  It was something I did every summer off the dock of the house we rented on Pensacola Beach… good times.

 

The thin telson beneath this crab indicates it is a male.  Photo: FWC

The thin telson beneath this crab indicates it is a male.
Photo: FWC

As I got older we switched from crab traps to hand-held crab nets.  We would spend hours searching the grass beds around Gulf Breeze collecting and cleaning these guys.  I remember cleaning over 60 of them once until my hands bled, that was about the time I thought I would let the commercial guys do this and I would just buy it from them!

As much fun as I had catching them, I had just as much fun cooking.  My wife and I would make deviled crab and one of my personal favorites of hers, crab meat baked on an English muffin with cheese.  Man o’ man.  What a great creature the crab.

 

There are about 4500 species of “true crabs” found on our planet and many are valuable as a seafood product.  In the Florida Panhandle it is the Blue Crab most seek out.  In recent years commercial and recreational crabbers have noticed a decline in their numbers.  Landings of blue crab ranged between 8 and 12 million pounds in Florida from 1982-1999 and since 2000 the landings have ranged from 4 to 8 million pounds.  Researchers with the Florida Fish and Wildlife Conservation Commission have run several models to determine why the decline in landings has occurred.  Though the decline in the Chesapeake may be due to overfishing, the models do not suggest this for Florida.  They are not sure why the decline has happened but do have data that support the argument that freshwater discharge during heavy rain events does impact their population in a negative way.  Some data suggest the increase in salinity during drought conditions has done the same.  Whatever the reason, many would like to see their numbers rebound to the 12 million lb. landings we had just a few years ago.

 

Blue crabs typically live to be 1-2 years old, though some have been aged to 5 years.  Males prefer the less saline waters of the upper estuary and the females can be found throughout the bay.  Males reproduce more than once in their lives providing the females with a sack of sperm called a spermatophore.  Females mate only once, just after their last molt.  Once she has received the spermatophore she heads for the mouth of the bay where the water is more saline, she may enter the Gulf of Mexico searching for the right habitat.  When she fertilizers her eggs they remain with her as a mass on her underside; the egg mass resembles a sponge.  The larva hatch from this mass and go through several development stages as they re-enter the estuary and begin the cycle again.

Male blue crab

Whatever the reason for their decline, and recent increase in price, these crustaceans remain a Gulf coast favorite and I for one hope they remain around for a long time.

PG

Author: Rick O’Connor – roc1@ufl.edu

Sea Grant Extension Agent in Escambia County

Rick O’Connor

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2015/10/23/national-seafood-month-blue-crabs/

Ghost Crabs… raiders of the night

Ghost Crabs… raiders of the night

 

For locals along the coast ghost crabs are as common as mockingbirds and mourning doves. Before Ivan, when the dunes were larger and closer to the road, viewing the white crabs scouring across the road at night in your headlights forced all into defensive driving maneuvers. And for those who have ever tried to catch one, all would agree it is one of the fastest animals on the beach.

 

The common ghost crab.  Photo: Virginia Institute of Marine Sciences

The common ghost crab. Photo: Virginia Institute of Marine Sciences

Ghost crabs (Ocypode quadrata) are members of the fiddler crab family. Like their fiddler crab cousins, they are more terrestrial than aquatic and dig burrows to protect themselves from predators and the intense heat of the midday sun. Though ghost crabs can be found in a variety of locations on the island, they are most frequently found between the mean high tide line and the upper portions of the primary dune line; typically on the Gulf side. Their “J” shaped burrows reach the water level below the sand and can run as deep as four feet. Larger individuals can dig deeper burrows and are often found further away from the water’s edge. These are crabs and thus still possess gills. Gills must be in contact with water in order to obtain needed oxygen. To do this ghost crabs have a gill chamber that will hold water for periods of time. The crabs can obtain water either at the bottom of their burrow or by running to the edge of the Gulf. And running is a good term for what they do. Once they have left the burrow they will lift five of their 10 legs above their head running on the remaining five. Running sideways they will have three in contact with ground in the direction they are going and two on the opposite side; if you look closely you can actually the remaining legs raised high in the air. When they tire, they will stop, make a 180° turn, and begin running again; resting their legs. They have reached speeds of 1.6 meters/second, which is 3.5 mph!

 

Ghost crabs are most active at night, though they are found at dawn and dusk and occasionally at midday. They feed on invertebrates at the surface zone such as mole crabs (sand fleas) and coquinas (bean clams). Dead fish and other animals found along the shoreline are also part of their diet, often dragging them back to their burrow. Unfortunately they are one of the predators of sea turtle hatchlings heading to the Gulf at night. Ghost crabs breed in late spring and early fall. The females will carry her developed eggs to the surf zone to release them. The developing young will return the following spring to mate and release their own eggs. Females may produce eggs in their second year but rarely live to do the same the third year. They are quite social with other crabs communicating, like their fiddler crab cousins, with body postures and claw movements. They are most active from March to December, plugging the entrance of their burrows and going dormant during the colder months of the year.

 

There has been concern about the impact of the oil spill on their numbers and the numbers of their prey, mole crabs and coquina. Our beaches did have small and large patches of oil that seeped down into the sand and then there were the methods used to remove the oil from the beach. At this point we do not know how hard their populations were impacted but scientists have collected data before and after the spill and are analyzing this now. However low their population dropped I am sure these resilient creatures will rebound and we will once again dodge them during our evening drives.

PG

Author: Rick O’Connor – roc1@ufl.edu

Sea Grant Extension Agent in Escambia County

Rick O’Connor

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2015/07/31/ghost-crabs-raiders-of-the-night/

Hermit Crabs Add to Summer Fun At North Florida Beaches

A room with a view: a stripped hermit crab sizes up a potential residence

A room with a view: a stripped hermit crab sizes up a potential residence

Summertime in north Florida is good. Among the premium experiences are leisurely hours at the beach.

For many this is a period of relaxation and the opportunity to casually examine what the surf has thrown on the beach. It can be the culmination of a summer vacation or a weekend reprieve from the contemporary insanity of 2015’s workaday grind.

The hermit crab is one commonly encountered native creature which is slow-moving and hard to miss observing. It scuttles along the shallow coastal waters in search of its immediate needs.

In most cases it is the next meal which prompts this member of the Pagurus genus to fitfully crawl about in the borrowed disguise of a gastropod. They are not particular which shell they occupy just so long as it fits their size and is transportable.

Likewise, they are not especially particular about their meals. Hermit crabs are omnivores which relentlessly scavenge for anything digestible in the shallow waters of much of the world.

Their family includes about 1100 members which differ in size, color and housing choices. Some, in other regions, will even lodge in immovable locations and depend on the tidal currents to provide for their nutritional requirements.

When times are good and the hermit crab has plenty to eat, it will outgrow it’s the shell which fate provided for its use. The search for a replacement requires probing, luck and can produce aggressive behavior between hermit crabs if appropriately sized shells are in short supply.

Without the shell a hermit crab is an easy meal for other denizens of the deep. If the shell is too small, the hermit crab cannot grow properly or withdraw into the shell completely which exposes it to the unending stream of predators.

The upper portion of their bodies is covered with a hard exoskeleton, but their abdomen is soft and vulnerable to attack. The long and pliable abdomen is useful for firmly holding to a vacant snail shell which provides the necessary protection.

The technique has proven very successful for the hermit crabs as a whole. Fossil records indicate these crustaceans have existed since the last days of the dinosaurs.

While hermit crabs live alone in the shells they procure, they are commonly found in colonies and compete for a variety of necessary resources and mates. Their collective activity has attracted the attention of many young beach goers.

The small, shy creatures have held unending fascination for generations of children. The hide and seek nature of their behavior retreating into shells at the first appearance of a threat increases the enticement.

The temptation to return home with a unique and diminutive pet has proven irresistible for many. One can only guess how many parents have first learned of their child’s decision by the aroma of a deceased hermit crab.

It is a good thing the visit to the beach is relaxing. To learn more about hermit crabs contact the nearest UF/IFAS Extension Office.

PG

Author: Les Harrison – harrisog@ufl.edu

Les Harrison is the UF/IFAS Wakulla County Extension Director, Agriculture and Natural Resources. He works with small and medium sized producers in the Big Bend region of north Florida on a wide range of topics. He has a Master’s of Science Degree in Agricultural Economics from Auburn University and a Bachelor of Science Degree in Journalism from the University of Florida.

Les Harrison

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2015/07/18/hermit-crabs-add-to-summer-fun-at-north-florida-beaches/

“Wanted” Sighting of Horseshoe Crabs!

“Wanted” Sighting of Horseshoe Crabs!

These curious ancient animals have been roaming the waters of the Atlantic and Gulf of Mexico for over 450 million years. Though they appear dangerous they are quite harmless and are actually more closely related to spiders and scorpions than crabs. Horseshoe crabs are not as common in Pensacola as they are in Panama City and Port St. Joe areas, but once were once found here and occasionally still are. Many coastal states have been concerned by the decline in their numbers. In the Chesapeake area where they were once very common, horseshoe crabs are harvested for their copper-based blood and also as bait for eel fishermen. The copper-based blood contains lysate which has been used to detect bacterial contamination in many drugs, as well as use for the diagnosis for some diseases.

 

The ancient horseshoe crab.  Photo UF/IFAS Communications

The ancient horseshoe crab. Photo UF/IFAS Communications

Though there is a fishery for them in Florida, the issue with most locals is just the loss of a really neat animal that has been around longer than the dinosaurs,. This time of year, near the full moon, horseshoe crabs begin to gather near nesting beaches to mate and lay eggs. The Florida Fish and Wildlife Conservation Commission is asking locals and tourists who find a horseshoe crab to report it. They are interested in sightings of both adults and juveniles (less than 4” in length), the date seen, the time, the location, and type of habitat if possible. To report you can visit their website (www.MyFWC.com), email at FWRI@horseshoe@fwc.state.fl.us , or call 1-866-252-9326

If you have any questions contact your county Sea Grant Agent for more information.

PG

Author: Rick O’Connor – roc1@ufl.edu

Sea Grant Extension Agent in Escambia County

Rick O’Connor

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2015/04/10/wanted-sighting-of-horseshoe-crabs/

Looking Out for Horseshoe Crabs

Horseshoe crabs spawning. Credit: Bill Hall, Univ. Delaware Sea Grant

Horseshoe crabs spawning.
Credit: Bill Hall, Univ. Delaware Sea Grant

Horseshoe crabs spawning on a beach. Credit: FL Fish & Wildlife Commission

Horseshoe crabs spawning on a beach.
Credit: FL Fish & Wildlife Commission

The female is the larger of the two horseshoe crabs. Credit: Fotosearch -Stock Photo

The female is the larger of the two horseshoe crabs.
Credit: Fotosearch -Stock Photo

Spring is here and that can only mean one thing, horseshoe crabs! That’s right it’s horseshoe crab survey time!

Each spring the scientists with the Florida Fish & Wildlife Conservation Commission (FWC) look for volunteers to report horseshoe crab sightings around the state as part of their annual horseshoe crab survey.

So, if you would like to be part of the research team, all you need to do is get out and walk along the beach and let FWC researchers know when you see horseshoe crabs. Please see the information at the end of this article for submission information. The following is some background information on horseshoe crabs.

About Horseshoe Crabs

  • The horseshoe crab is found on shores of the western Atlantic Ocean ranging from Maine to Mexico. Fossils of horseshoe crab ancestors show that these animals have been around for over 350 million years – before the age of dinosaurs. Therefore, it is no surprise that scientists typically refer to horseshoe crabs as “living fossils.”
  • Interestingly, horseshoe crabs are not really crabs at all! As it turns out, they are more closely related to spiders and scorpions than they are to true crabs. This is because unlike true crabs, horseshoe crabs do not have antennae or jaws, and their legs are similar to those found on spiders.
  • Currently, horseshoe crabs are being harvested commercially for three purposes in the United States: bait (conch & eel fisheries); marine life (aquarium trade, research, etc.); and biomedical (for blood).
  • Compared to other states, especially along the Atlantic coast, Florida does not have a large horseshoe crab fishery.  The primary harvest in Florida is for marine life.
  • Horseshoe crabs are ecologically important. During certain times of the year, horseshoe crabs lay billions of eggs on beaches. These eggs are an important food source for migrating birds and the marine wildlife.
  • Horseshoe crabs are also directly important to humans because research on their compound eyes has lead to a better understanding of the human visual system.
  • In addition, horseshoe crab blood is widely used by the biomedical industry. Special cells in their blood (which by the way is blue) are used to test for bacterial contamination in our blood supplies and in the production of many commercial drugs. A horseshoe crab’s blood contains hemocyanin, a copper – based molecule that gives it a blue color.
  • Finally, the material that makes up their exoskeleton (chiton) is used to make contact lenses, skin creams, and hair sprays.
The blood of the horseshoe crab is blue because it is copper-based. Credit: FL Fish & Wildlife Commission

The blood of the horseshoe crab is blue because it is copper-based.
Credit: FL Fish & Wildlife Commission

Horseshoe Crab Anatomy

  •  The tail of the horseshoe crab is often thought to be a weapon by many people. However, the horseshoe crab is actually harmless and the tail is used to dig through sand and to turn the crab upright if it is accidentally turned over.
  • The first pair of legs can be used to distinguish between males and females. Males use their specialized front legs, called claspers, to hold on to the female during spawning.

Project Objectives and Goals

Currently, horseshoe crabs are being over-harvested in some states. The management plan issued by the Atlantic States Marine Fisheries Commission requires that all Atlantic coastal states must identify horseshoe crab spawning beaches.

With your help! – FWC’s goal is to identify horseshoe crab spawning beaches around Florida.

How can you help?

FWC is asking the public to report sightings of horseshoe crab activities. The information that the researchers would like to collect from you is the following:

  • Date and time of your sighting.
  • Location of your sighting.
  • Whether or not horseshoe crabs were spawning.
  • A rough estimate of the number of horseshoe crabs seen.

Spawning behavior of horseshoe crabs is best observed within three-days before and after a full or new moon on sandy beaches with low wave action.

If you want to be more involved, you can contact the FWC researchers about collecting data on abundance of male and female horseshoe crabs, and on sizes of individuals. You can contact FWC using any of the following methods:

Go to MyFWC.com/Contact and click on the “Submit a Horseshoe Crab Survey” link, then “Florida Horseshoe Crab Spawning Beach Survey,” or go directly to http://www.surveymonkey.com/s/horseshoe_crab

  1. You can also report findings via email at horseshoe@MyFWC.com
  2. Or call toll-free at 1-866-252-9326

If you have any questions please let me know. Enjoy your beach walks and “crab” watching.

(Bill Mahan is a FL Sea Grant Agent and Director of the Franklin UF-IFAS Extension Program. Contact him at (850) 653-9337, 697-2112 x 360; via e-mail at bmahan@ufl.edu; or Facebook http://www.facebook.com/UFIFASFranklinExtension

PG

Author: bmahan – bmahan@ufl.edu

bmahan

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2013/04/19/looking-out-for-horseshoe-crabs/

Be on the lookout for horseshoe crabs

 Bill Mahan
County Extension Director
Franklin
bmahan@ufl.edu
 

Spring is around the corner and that can only mean one thing, horseshoe crabs! That’s right it’s horseshoe crab survey time!
Horseshoe crab blood looks blue. Photo Credits: Florida Fish and Wildlife Conservation Commission

Each spring the scientists Florida Fish & Wildlife Research Institute (FWRI) look for volunteers to report horseshoe crab sightings around the state as part of their annual horseshoe crab survey. So, if you would like to be part of the research team, all you need to do is get out and walk along the beach and let FWRI researchers know when you see horseshoe crabs. Please see the information at the end of this article for submission information. The following is some background information on horseshoe crabs.
Horseshoe crabs arrive at a spawing beach. Photo Credits: Florida Fish and Wildlife Conservation Commission

About Horseshoe Crabs
Horseshoe crabs mass spawing. Photo Credits: Florida Fish and Wildlife Conservation Commission
•The horseshoe crab is found on shores of the western Atlantic Ocean ranging from Maine to Mexico. Fossils of horseshoe crab ancestors show that these animals have been around for over 350 million years – before the age of dinosaurs. Therefore, it is no surprise that scientists typically refer to horseshoe crabs as “living fossils.”
•Interestingly, horseshoe crabs are not really crabs at all! As it turns out, they are more closely related to spiders and scorpions than they are to true crabs. This is because unlike true crabs, horseshoe crabs do not have antennae or jaws, and their legs are similar to those found on spiders.
•Currently, horseshoe crabs are being harvested commercially for three purposes in the United States: bait (conch & eel fisheries); marine life (aquarium trade, research, etc.); and biomedical (for blood).
•Compared to other states, especially along the Atlantic coast, Florida does not have a large horseshoe crab fishery.  The primary harvest in Florida is for marine life.
•Horseshoe crabs are ecologically important. During certain times of the year, horseshoe crabs lay billions of eggs on beaches. These eggs are an important food source for migrating birds and the marine wildlife.
•Horseshoe crabs are also directly important to humans because research on their compound eyes has lead to a better understanding of the human visual system.
•In addition, horseshoe crab blood is widely used by the biomedical industry. Special cells in their blood (which by the way is blue) are used to test for bacterial contamination in our blood supplies and in the production of many commercial drugs. A horseshoe crab’s blood contains hemocyanin, a copper – based molecule that gives it a blue color.
•Finally, the material that makes up their exoskeleton (chiton) is used to make contact lenses, skin creams, and hair sprays.
Horseshoe Crab Anatomy
•The tail of the horseshoe crab is often thought to be a weapon by many people. However, the horseshoe crab is actually harmless and the tail is used to dig through sand and to turn the crab upright if it is accidentally turned over.
•The first pair of legs can be used to distinguish between males and females. Males use their specialized front legs, called claspers, to hold on to the female during spawning.
Project Objectives and Goals

Currently, horseshoe crabs are being over-harvested in some states. The management plan issued by the Atlantic States Marine Fisheries Commission requires that all Atlantic coastal states must identify horseshoe crab spawning beaches.

With your help! – FWRI’s goal is to identify horseshoe crab spawning beaches around Florida.

How can you help?

FWRI is asking the public to report sightings of horseshoe crab activities. The information that the researchers would like to collect from you is the following:
•Date and time of your sighting.
•Location of your sighting.
•Whether or not horseshoe crabs were spawning.
•A rough estimate of the number of horseshoe crabs seen.
Spawning behavior of horseshoe crabs is best observed within a few days before and after a full or new moon on sandy beaches with low wave action.

If you want to be more involved, you can contact the FWRI researchers about collecting data on abundance of male and female horseshoe crabs, and on sizes of individuals. You can contact FWRI using any of the following methods:
1.Online survey: www.floridamarine.org/horseshoe_crab/
2.E-mail at FWRI @: horseshoe@fwc.state.fl.us
3.Call them toll-free at: 1-866-252-9326
4.Download the survey at: http://myfwc.com/media/202243/horseshoecrabdatasheet.pdf and mail it to:
Florida Fish and Wildlife Conservation Commission

Sen. George Kirkpatrick Marine Lab

Attn: Florida Horseshoe Crab Survey

11350 SW 153rd CT

Cedar Key, FL 32625
If you have any questions please let me know. Enjoy your beach walks and crab watching.

Panhandle Outdoors

Permanent link to this article: http://franklin.ifas.ufl.edu/newsletters/2012/02/04/be-on-the-lookout-for-horseshoe-crabs/