[6] These horseshoe crabs can be found to exist throughout the Southeast Asia region in shallow waters with soft, sandy bottoms or extensive mud flats. Mangrove Horseshoe Crab Carcinoscorpius rotundicauda (Latreille, 1802) "In this ancient ritual that predates the dinosaurs, thousands of horseshoe crabs emerge from the water to spawn in the pre-dawn light." [5] Each individual has six pairs of appendages. , another cancer drug. [5] Studies have found that mangrove horseshoe crabs have a strong preference for insect larvae over the other organisms on which it also feeds.[8]. A third analogue was capable of sneaking into cancer cells without popping them, which could be useful for designing a scaffold for drug delivery into melanoma cells. Click here for instructions on how to enable JavaScript in your browser. It is found in countries like India, Malaysia, Thailand, Hong Kong Indonesia, the Philippines, and Singapore. The marginally-spined middle is called the opisthosoma, and the rear extension that looks like a spike is the telson, which is commonly described as the tail. Thousands of the horseshoe crabs are caught by local fishermen. It is estimated that the American species of horseshoe crab diverged from the three Indo-Pacific species approximately 135 million years ago. During the mating period, the males will follow and cling to the backs of their potential mates using modified prosomal appendages for long periods of time before the egg-laying has occurred. These gills are used for propulsion to swim and to exchange respiratory gases. It is the only species in the genus Carcinoscorpius. Horseshoe crabs secrete a variety of host defense peptides, but one in particular, tachyplesin-I (TI), has captured attention as a promising anticancer drug lead. However, some reports show that the crabs are toxic. [2] Fossils of horseshoe crabs that have been dated to over 400 million years ago look almost identical to those species that are still alive today. There are four species of horseshoe crabs in the world, two of which can be found in Singapore the Mangrove Horseshoe Crab (Carcinoscorpius rotundicauda) and the Coastal Horseshoe Crab (Tachypleus gigas). [2], The basic body plan of a horseshoe crab consists of three parts: the prosoma, the opisthosoma and the telson. Yet evolution isn’t perfect, and nature doesn’t necessarily have a solution for everything. This is the smaller of our horseshoe crabs. The Mangrove Horseshoe crab has blue blood. Males find their female mates with the use of visual and chemoreceptive signals. The Mangrove Horseshoe crab has blue blood. In the study, they found an uneven distribution of the horseshoe crabs throughout Hong Kong, with a greater abundance found in the western waters. of the Atlantic horseshoe crab possesses a unique molecule that quickly coagulates in the presence of microbial toxins. Mangrove Horseshoe crabs swim upside down. The horseshoe crab isn’t good at doing much, but it’s shockingly good at surviving. Think of the bacterium as a water balloon, as shown in Figure 1. Nature knows to quit when it’s ahead–just take a look at the horseshoe crab. Many chemists today are repurposing host defense peptides to target not only microbes, but cancer as well. While different host defense peptides have different mechanisms of action, many of them kill bacteria by interacting with the bacterium’s negatively charged outer membrane. Nature knows to quit when it’s ahead–just take a look at the horseshoe crab. The Limulidae are the only recent family of the order Xiphosura, and contains all four living species of horseshoe crabs: Carcinoscorpius rotundicauda, the mangrove horseshoe crab, found in South and Southeast Asia Total height: 61.5 cm Weight without base: 315 g Now, chemists are turning their sights to the horseshoe crab once again, this time in search of a potential cure for cancer: a recent study from researchers at the Queensland University of Technology shows that small modifications to a naturally occurring horseshoe crab protein make it a promising drug lead for treating skin cancer.=. figures by Jovana Andrejevic. To make the molecule more stable in human blood, the researchers joined the two ends of the molecule like two ends of a string to create a cyclic version of TI called cTI. [6] This is the habitat for which it gains its common name: mangrove horseshoe crab. The dialogue between nature and synthetic chemistry yields some of the most promising and revolutionary medications. Horseshoe crabs have evolved to produce a class of proteins to combat microbial infections called, , which are small, positively-charged proteins capable of killing bacteria. Ideally, like two poles of a magnet, these positively charged host defense peptides should only be attracted to and kill cancer cells, while leaving healthy cells alone. Your email address will not be published. The horseshoe crab isn’t good at doing much, but it’s shockingly good at surviving. The ingested food then enters the cuticle-lined oesophagus and then the proventriculus. All four extant species of horseshoe crabs are anatomically very similar. In the spring, horseshoe crabs migrate from the deeper water to the shallow, muddy areas. The mangrove horseshoe crab, Carcinoscorpius rotundicauda, is a chelicerate arthropod found in marine and brackish waters. Many medications were invented in the lab, such as. The first pair, the chelicerae, is used to place food in its mouth. This living fossil continues to trudge through shallow, brackish waters, its large tank-like shell protecting its soft, wriggly underbody, looking for tiny worms and mollusks to scoop into its belly, just like it did millions of years ago. [9] Their eggs are large, and after a couple weeks, the eggs hatch into miniature versions of the adults. Since its origins 450 million years ago, the animal has remained relatively unchanged. The Mangrove horseshoe crab (Carcinoscorpius rotundicauda) and the Coastal horseshoe crab (Tachypleus gigas) have similar ranges. In addition, the female does not choose her mate. [5], This species occurs only in Asia around the Indo-West Pacific region where the climate is tropical or subtropical. Horseshoe crabs have evolved to produce a class of proteins to combat microbial infections called host defense peptides, which are small, positively-charged proteins capable of killing bacteria. This page was last modified on 6 April 2016, at 10:14. Located behind their legs are book gills. The biology, ecology and breeding patterns of C. rotundicauda and the two other Asian horseshoe crab species, Tachypleus gigas and Tachypleus tridentatus, have not been as well documented as those of the North American species Limulus polyphemus. ago, the animal has remained relatively unchanged. After a very long time i have read such an amazing article, The mangrove horseshoe crabs (Carcinoscorpius rotundicauda) are often found buried in the mudflats when the tide recedes while coastal horseshoe crabs (Tachypleus gigas) move out with the tide. The Mangrove Horseshoe Crab is called the "living fossil" because it has been on Earth 20 million years before dinosaurs. [9] Once a mate is found, the female digs a hole and lays the eggs while the male externally fertilizes them. The rest of the legs are used for locomotion and are known as pusher legs. Early in 2019, researchers in the Peptide Therapeutics and Membrane Biology Research Group at Queensland University of Technology evaluated the ability of TI to kill a variety of cancer cells. The roe is mixed with salad for that extra bite. As a result, the pharmaceutical industry uses horseshoe crab blood to test for microbial contaminants in anything that might end up inside of a person’s body. [3] The mangrove horseshoe crab grows up to 40 centimeters in length (including the tail), and its whole body is protected by a hard, dark brown carapace. [8] Lacking jaws, it grinds up the food with bristles on its legs and places it in its mouth using its chelicerae. It is sometimes encountered in our northern shores, in mudflats, mangroves and shores nearby. Photo taken by Steve Greer at Delaware Bay, USA (pending approval). Horseshoe crabs are remarkable living fossil that evolved 450 million years ago. Despite its name, it is more closely related to spiders and scorpions (all are in the subphylum Chelicerata) than to crabs. While different host defense peptides have different mechanisms of action, many of them kill bacteria by interacting with the bacterium’s negatively charged outer membrane. In addition, they have two median eyes, two rudimentary lateral eyes, and an endoparietal eye on their carapace and two ventral eyes located on the underside by the mouth. These analogues were almost 3.5 times more selective for melanoma cells than the original TI molecule. The Mangrove Horseshoe crab is found in the West Pacific Region. In Thailand the eggs are eaten in a dish known as Yam Khai Maengda, a kind of salad made with the boiled eggs. They predict this unevenness is due to the estuarine hydrography in the western waters, influenced by the Pearl River. The Mangrove Horseshoe crab has ten eyes. Horseshoe crab species with low spawning densities and 1:1 sex ratios, such as the mangrove horseshoe crab, are found to be monogamous. There are four extant species of horseshoe crab. Horseshoe crabs are commonly known by biologists around the world as a living fossil because they have remained practically unchanged in terms of shape and size for millions of years. Most horseshoe crabs will not even make it to the larval stage before being eaten. Horseshoe crabs are also pretty good pharmaceutical chemists. Meanwhile, healthy cells typically have a neutral membrane. Take, for example, one of the horseshoe crab’s biggest contributions to medical science: its blood. After developing nine synthetic versions of cTI, two of them stood out for their high potency and selectivity for melanoma cells. [11], From Infogalactic: the planetary knowledge core, CS1 maint: multiple names: authors list (, File:Carcinoscorpius rotundicauda (Chonburi).jpg, International Union for Conservation of Nature, "Reproductive behavior in horseshoe crabs: does density matter? Well, because even if cancer isn’t a problem, the horseshoe crab is faced with myriads of other medical maladies that it has learned to combat. The blood of the Atlantic horseshoe crab possesses a unique molecule that quickly coagulates in the presence of microbial toxins. The blood contains a chemical called Limulus amoebocyte lysate (LAL) that can be used to detect pathogens and their endotoxins. The data suggests that these cTI analogues are promising leads for melanoma drug development, and that cTI in general is a versatile starting point for cancer drug development. For example, invading microbes are an issue that horseshoe crabs are quite familiar with. Your email address will not be published. If the egg survives, the larval horseshoe crab will hatch from the egg after about two weeks or more. Currently you have JavaScript disabled. Horseshoe crabs might seem like medical miracle workers, and indeed, in some ways they are—horseshoe crabs make medically relevant molecules that synthetic chemists couldn’t even imagine.