Horseshoe crabs are marine animals of the suborder Limulacea, in the order Decapoda. They live primarily on soft bottoms from near-shore to deepwater habitats and they have a horseshoe shape (hence their name) which ends with an angular face. These stubby little creatures can be found throughout the world in both tropical and temperate regions.
The horseshoe crab is a living fossil that has existed for some 450 million years from way back when they were just tadpole-shaped worms with no shell at all to their current state as an animal which dates so far back, it’s hard to say what this little crab might look like if it were still in the early developmental stages.
They are not actually crabs at all, but marine animals with an arthropod exoskeleton and four pairs of legs on their thorax. They have strange, long appendages that protrude from either side of their head which can be used to detect movement or electrical fields.
Horseshoe crab habitat
Horseshoe crabs have a wide habitat and are found in temperate, subtropical, tropical habitats. They can be found on the ocean floor or near its surface from intertidal zones to depths of over 400 feet (120 m). All species prefer hard substrates such as sand with rocks, rubble, or gravel for their claws to cling to.
Their population range is from the United States east coast and along the Gulf Coast, Caribbean Sea, Mediterranean Sea (in Croatia), Indian Ocean, China’s Yangtze River Delta region in Sichuan Province, Korea Strait, and south of Japan. The only horseshoe crab not found on a continental shelf is Triops cancriformis, which lives in temporary ponds.
The horseshoe crab’s habitat has been greatly reduced by coastal development and overfishing; it is only found where the living conditions are not disturbed or damaged. It faces a number of threats including shoreline erosion, pollution from stormwater runoff containing pesticides and fertilizers, and marine debris.
They have a wide habitat and are found in temperate, subtropical, tropical habitats. They can be found on the ocean floor or near its surface from intertidal zones to depths of over 400 feet (120 m). All four species prefer hard substrates such as sand with rocks, rubble, or gravel for their claws to cling to.
Their population range is from the United States east coast and along the Gulf Coast, Caribbean Sea, Mediterranean Sea (in Croatia), Indian Ocean, China’s Yangtze River Delta region in Sichuan Province, Korea Strait, and south of Japan.
Horseshoe crab mating
When two horseshoe crabs mate, they are both on the same level. The male crab will insert his spermatophore into the female’s fertilization chamber and release sperm cells while simultaneously releasing the second packet of sperm from its rear end to enter her oviducts for reproduction. This process is called “semelparity” and it is the first time that female horseshoe crabs release eggs.
A female horseshoe crab can lay as many as 50,000 eggs at one time. The eggs are deposited in a “pale” or egg mass on the sand and left unattended. They live to be about 100 years old, so they have plenty of time for their offspring to hatch and develop into adults.
The eggs are typically left unattended and hatch after about a year. One of the first things that young horseshoe crabs do is find the nearest ocean because they cannot survive without saltwater for long periods of time. They also have to avoid predators like birds, gulls, seals, sharks, and raccoons while on their journey to the ocean.
The female typically lay eggs about once a year, and males fertilize them with sperm from their rear end! It takes one year for the eggs to hatch into baby horseshoe crabs that then have to go on an amazing journey across the land just so they can reach saltwater.
Horseshoe crab egg
A horseshoe crab is a large marine creature that lives in the sand at the bottom of shallow sea waters. The female lays eggs and then buries them deep into the sand to protect them from predators such as fish, starfish, spoon worms, wolf eels (a type of worm), crabs, and sometimes other horseshoe crabs.
The eggs stay buried in the sand for about three weeks until they hatch, and then the baby horseshoe crab larvae swim out to sea where they develop into adult horseshoe crabs.
The females can lay eggs year-round, but they are most prolific during the summer months.
Horseshoe crab babies
Horseshoe crab babies are born from eggs that the mother horseshoe crabs lay. It is for this reason that they are also called “laid-eggers.” These baby horseshoes, or larvae as scientists call them, have a life span of only about eight weeks before becoming adults and laying their own eggs. They reach adulthood by first turning into a nauplius stage, which is the second stage of development for horseshoe crab larvae.
When they are born as eggs, their bodies have three pairs of appendages at the front and one pair on top that later becomes claws. Horseshoes tend to be red or brown before they turn completely blue.
Horseshoe crabs are very good at guarding their eggs, but they do not protect them from predators such as seagulls because the crabs cannot fly and move fast enough on land to catch the birds in flight. However, horseshoes usually lay more than one clutch of eggs so that if some or all of them are destroyed, the mother still has a chance to raise her young.
Horseshoe crab lifespan
The lifespan of a horseshoe crab starts out around 20 years old and it can live up to 100 years. The female will lay eggs in the water close to where they were hatched which is done by attaching themselves onto seagrasses or rocks with their egg pouch facing down into the water. Female crabs generally have one clutch per year, and this is usually around the month of May.
Horseshoe crab sting
One of the most common ways to get a horseshoe crab sting is by touching one. These crustaceans have thin, brittle spines that lay flat against their shells when they are at rest, but these can quickly flip upright and jab into anything nearby if they are disturbed or threatened in any way. When handling them carelessly, it is easy for the spine to stab through a finger or hand.
The stings are generally not serious and will heal on their own in time, but they should still be taken seriously as some people have been known to experience allergic reactions from this type of puncture wound that can lead to anaphylactic shock. In the worst case, the victim may lose consciousness and die.
This type of puncture wound can also lead to tetanus if it is not properly cared for. It is important that a person who has been stung by a horseshoe crab clean the skin with rubbing alcohol or soap within five minutes of being injured before applying an antiseptic ointment or a dry bandage.
Horseshoe crab blood
Horseshoe crabs have a blue blood that contains copper and hemocyanin, which gives them the ability to survive in both saltwater and freshwater. The horseshoe crab’s circulatory system is different from humans because it utilizes its legs as a pump for its internal organs instead of having a heart. These animals were once abundant, but their numbers have dwindled due to the depletion of habitats and overfishing.
Horseshoe crab blood uses
Horseshoe crabs use hemocyanin, a copper-containing molecule that carries oxygen in their blood. Unlike most vertebrates which carry the bulk of their iron in hemoglobin (which is what turns meat pink), they have no hemoglobin and are blue due to the copper present in this form of protein. To compensate for having to find another way of getting oxygen to the tissues, their blood is extremely viscous and contains about 40% more salt than other animals (approximately 25 times that of humans).
The horseshoe crab has blue blood. The hemoglobin in their blood contains copper, which is an essential element for maintaining a sufficient oxygen supply throughout the body’s tissues and organs.
Copper also helps to fight off bacteria that could cause infection.
In addition, their blood contains an enzyme called amebocyte lysate. Amoebocytes and macrophages are cells that work together to fight infections. Lysing the amoebocytes releases a substance with clotting properties that helps the horseshoe crab’s blood to clot faster than human blood.