Why are horseshoe crabs important

Horseshoe crabs have been around for more than million years, making them even older than dinosaurs. They look like prehistoric crabs, but are actually more closely related to scorpions and spiders. The horseshoe crab has a hard exoskeleton and 10 legs, which it uses for walking along the seafloor. The body of the horseshoe crab is divided into three sections. The first section is the prosoma, or head.

It's the largest part of the body and contains much of the nervous and biological organs. The head has the brain, heart, mouth, nervous system, and glands—all protected by a large plate. The head also protects the largest set of eyes. Horseshoe crabs have nine eyes scattered throughout the body and several more light receptors near the tail.

The two largest eyes are compound and useful for finding mates. The other eyes and light receptors are useful for determining movement and changes in moonlight. The middle section of the body is the abdomen, or opisthosoma.

It looks like a triangle with spines on the sides and a ridge in the center. The spines are movable and help protect the horseshoe crab. On the underside of the abdomen are muscles, used for movement, and gills for breathing. It's long and pointed, and although it looks intimidating, it is not dangerous, poisonous, or used to sting. Horseshoe crabs use the telson to flip themselves over if they happen to be pushed on their backs. Female horseshoe crab are about one-third larger than the males.

They can grow to be 18 to 19 inches 46 to 48 centimeters from head to tail, while the males are approximately 14 to 15 inches 36 to 38 centimeters.

The horseshoe crab species found around the United States Limulus polyphemus lives in the Atlantic Ocean along the North American coastline. There are three other species of horseshoe crab worldwide, which are located in the Indian Ocean and in the Pacific Ocean along the coast of Asia. Horseshoe crabs utilize different habitats depending on their stage of development. The eggs are laid on coastal beaches in late spring and summer. After hatching, the juvenile horseshoe crabs can be found offshore on the sandy ocean floor of tidal flats.

Adult horseshoe crabs feed deeper in the ocean until they return to the beach to spawn. Many shorebirds, migratory birds, turtles, and fish use horseshoe crab eggs as an important part of their diet.

Horseshoe crabs live around North America and Asia. They are threatened by fishing, the medical industry and habitat loss. During Beta testing articles may only be saved for seven days. Create a list of articles to read later. You will be able to access your list from any article in Discover. Nature plays a huge part in the medicines we rely on every day. And when it comes to vaccines, we have horseshoe crabs and their blood to thank for keeping us safe.

Horseshoe crabs are older than the dinosaurs. They've been around for million years, which means they watched the rise and fall of millions of other species, and survived ice ages. As well as being incredible 'living fossils', they have also helped to keep most of us alive. If you have ever had a vaccine, chances are that it was tested for safety using horseshoe crab blood.

And they're about to save even more lives, because they're playing their part in the creation of a Covid injection. Horseshoe crab blood is a bright shade of blue, as well as having remarkable antibacterial properties that have proved invaluable to the medical industry. Image via Business Insider. Horseshoe crab blood is bright blue. It contains important immune cells that are exceptionally sensitive to toxic bacteria.

When those cells meet invading bacteria, they clot around it and protect the rest of the horseshoe crab's body from toxins. Scientists used these clever blood cells to develop a test called Limulus Amebocyte Lysate, or LAL, which checks new vaccines for contamination. This technique has been used all over the world since the s to stop medical professionals giving out jabs full of bad bacteria that could make humans very sick.

It's great for humans, because vaccines save us from all sorts of unwanted diseases, including measles and mumps. It's not so great for the horseshoe crabs: thousands of them are rounded up and bled every year.

A group of horseshoe crabs gather together to spawn. The world is rushing to find a safe vaccine to fight Covid, the viral lung disease which has swept the planet. More than different vaccines are being tested in the hope that one will work. The successful jabs will have to be carefully checked before they are rolled out. In many parts of the world, researchers will be relying on horseshoe crab blood in those important tests.

And since we'll want to vaccinate millions of people in a short space of time, horseshoe crabs could play a big part. There are four species of horseshoe crab. These are the tri-spine horseshoe crab Tachypleus tridentatus , the coastal horseshoe crab Tachypleus gigas and the mangrove horseshoe crab Carcinoscorpius rotundicauda. The fourth is the American horseshoe crab Limulus polyphemus which lives along the east coast of North America, with a particularly large number going to the beaches of the Delaware Bay to mate each year.

These crabs may look prehistoric, but they do an important job of supporting other animals around them: their eggs are a nourishing snack for migrating birds. They are also good for fishermen because they help keep the sediment around coastlines healthy. Most nesting activity takes place during high tides around the time of a new or full moon.

Horseshoe crab larvae emerge from their nests several weeks after the eggs are laid. Juvenile horseshoe crabs look a lot like adults except that their tails are smaller. The young and adult horseshoe crabs spend most of their time on the sandy bottoms of inter-tidal flats or zones above the low tide mark and feed on various invertebrates.

Horseshoe crabs are an important part of the ecology of coastal communities. Their eggs are the major food source for shorebirds migrating north, including the federally-threatened red knot. These shorebirds have evolved to time their migrations to coincide with peak horseshoe crab spawning activity, especially in the Delaware and Chesapeake Bay areas.

They use these horseshoe crab beaches as a gas station, to fuel up and continue their journey. Many fish species as well as birds feed on horseshoe crab eggs in Florida. Adult horseshoes serve as prey for sea turtles, alligators, horse conchs, and sharks. Horseshoe crabs are also extremely important to the biomedical industry because their unique, copper-based blue blood contains a substance called "Limulus Amebocyte Lysate", or "LAL".

This compound coagulates or clumps up in the presence of small amounts of bacterial toxins and is used to test for sterility of medical equipment and virtually all injectable drugs. Anyone who has had an injection, vaccination, or surgery has benefited from horseshoe crabs! Additionally, research on the amazing and complex compound eyes of horseshoe crabs has led to a better understanding of human vision. Horseshoe crabs are also used in several fisheries.

The marine life fishery collects live horseshoe crabs for resale as pets in aquariums, research subjects, or as educational specimens, and both the American eel and whelk fisheries use horseshoe crabs as bait along many parts of the Atlantic coast.

Threats to horseshoe crabs and research efforts Horseshoe crab numbers are declining throughout much of their range. Currently, with the help of the public, biologists at the Fish and Wildlife Research Institute are documenting nesting sites of horseshoe crabs throughout the state. If you see horseshoe crabs mating and would like to report a sighting, please visit the Report Sightings page for more information.

No, horseshoe crabs are in a class by themselves; they are more closely related to spiders, scorpions, and ticks. They are different from true crabs because they have no antennae and no mandibles mouth parts for grinding food. Like spiders, they have a pair of chelicerae small appendages for moving food into the mouth. Yes and no, that idea comes from the fact that million years ago, ancestors of horseshoe crabs were abundant.