Tag Archive: horseshoe

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/

An Ancient Mariner… the horseshoe crab

An Ancient Mariner… the horseshoe crab

Talk about weird and cool at the same time! The horseshoe crab is one of the oldest living species we have in the Gulf of Mexico.  Fossils of this animal date back to almost 500 million years… this is before there was such a thing as fish!  The separating of Pangea, the rise and fall of the dinosaurs, oh what stories these guys could tell!  And they are here today, trudging along in the soft sands of estuaries along the Atlantic and Gulf coasts… but they seem to be on the decline.  After all they have been through… they may be slipping away.

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

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

Actually, horseshoe crabs are not crabs at all. They belong to the same large group of animals the crabs belong to, Arthropods, but differ from true crabs in that they have fewer jointed legs and no antennae.  They are actually more closely related to spiders and scorpions.  There are 4 species remaining on Earth. Limulus polyphemus is the local variety with the other three living in Asia.  They are tolerant of a wide range of environmental conditions.  Huge swings in water temperature and salinity do not bother them.  This is not surprising considering all of the environmental changes that have occurred since the species first appeared on the planet.  They are scavengers, plowing through the soft bottom of estuaries, they feed on worms, mollusk, and whatever else their crop-gizzard system can breakdown.  Their protective shell deters many predators; most horseshoe crabs meet their fate on the beach – where they must go to breed.

 

Breeding occurs all year in Florida. It typically takes place three days before and after the new or full moon.  The smaller males come near shore and patrol for the oncoming females.  As the females are intercepted the males will use their “hook” to hold on and the pair ride onto the beach.  This usually happens at night (though not always) during the peak of a spring high tide.  The female digs a small depression and deposits between 200 and 300 eggs, the male fertilizes them, and the female buries them.  They leave the young on their own for a month, at which time the next spring tide arrives and the larva, which resemble trilobites, emerge.  Many fall prey to shorebirds and many adults actually become stranded on the beach during nesting and die.

 

So why the population decline?

Well, they do tolerate large swings in environmental change, so increase temperatures, rainfall, salinities, do not bother them. Studies have shown that they are actually quite tolerant of many of the pollutants, including oil, we discharge into our bays – though mercury is a problem for the developing trilobite larva.  Along the Atlantic coast the animals are collected for bait and the biomedical industry.  Horseshoe crabs are used in eel traps and there are several medical uses for their blood.  Some biomedical industries collect the crabs, remove some of the blood, and return them – but not all survive this.  A big problem they are facing, and this would be closer to home, is the loss of nesting habitat.  Seawalls, jetties, groins, and coastal development in general have disturbed nesting beaches.

 

That said, they seem to be making a comeback on Pensacola Beach. There have been sightings at both Big and Little Sabine.  We would like to record where they are nesting in the panhandle.  If you would like to help – the full moon for the next few months will occur on March 22, April 22, May 21, and June 20.  The new moon will occur March 8, April 7, May 6, and June 4.  If you do see a horseshoe crab please contact me at (850) 475-5230, or email at roc1@ufl.edu.

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/2016/03/11/an-ancient-mariner-the-horseshoe-crab/

“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/