{"product_id":"atlantic-horseshoe-crab-limulus-polyphemus","title":"Atlantic Horseshoe Crab (Limulus polyphemus)","description":"\u003cp\u003eThe Atlantic Horseshoe Crab is one of the most extraordinary animals available in the marine hobby, and one of the most important animals on Earth. Despite its name, it is not a true crab or even a crustacean; it is more closely related to spiders and scorpions, representing a highly divergent lineage with a deep evolutionary history stretching back over 400 million years. It has remained virtually unchanged across that vast span of time, earning it the title of living fossil. Its domed, helmet-shaped carapace, multiple jointed legs, and long spike-like telson tail give it a silhouette unlike anything else in the hobby, and for the marine enthusiast with the right setup, keeping one is a genuinely humbling experience. This listing comes with full transparency: the Atlantic Horseshoe Crab is a magnificent and long-lived animal that demands a very specific commitment from the hobbyist, and it is not suitable for most home aquarium setups at adult size. Juveniles, however, can be maintained responsibly in appropriately planned systems by experienced keepers.\u003c\/p\u003e\n\u003ch3\u003eWhy we love it\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eOne of the oldest surviving animal lineages on the planet; a living connection to the Ordovician period kept in your own home\u003c\/li\u003e\n\u003cli\u003eUtterly unique silhouette and movement style, unlike anything else in the marine hobby; an instant conversation piece\u003c\/li\u003e\n\u003cli\u003eA tireless substrate worker; adults burrow through sediments to feed on polychaetes, bivalves, and other benthic fauna, constantly aerating and turning the sandbed\u003c\/li\u003e\n\u003cli\u003eFully peaceful toward all fish and most larger invertebrates; poses no threat to anything it cannot physically bulldoze or eat\u003c\/li\u003e\n\u003cli\u003eA fascinating and scientifically significant animal that carries immense ecological and medical importance in the natural world\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSuggested parameters\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eTemperature: 18 to 24°C (65 to 75°F); this is a temperate to subtropical species that is an ecological generalist capable of tolerating a broad temperature and salinity range, but sustained tropical reef temperatures at the higher end of reef norms are not ideal long-term\u003c\/li\u003e\n\u003cli\u003eSalinity: 1.023 to 1.025 SG\u003c\/li\u003e\n\u003cli\u003epH: 8.1 to 8.4\u003c\/li\u003e\n\u003cli\u003eAlkalinity: 8 to 12 dKH\u003c\/li\u003e\n\u003cli\u003eNitrate: Under 20 ppm; clean, well-oxygenated water with stable parameters is essential\u003c\/li\u003e\n\u003cli\u003eStable salinity and dissolved oxygen levels are particularly important; Horseshoe Crabs are sensitive to rapid environmental fluctuations\u003c\/li\u003e\n\u003cli\u003eCopper-based medications are toxic to all invertebrates and must never be used\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eCare and temperament\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eDifficulty: Advanced; not a casual addition, long-term planning around adult size is mandatory\u003c\/li\u003e\n\u003cli\u003eTemperament: Peaceful; does not attack other tank inhabitants but will unintentionally disturb corals, dislodge rockwork, and overturn invertebrates on the substrate while bulldozing and burrowing during feeding\u003c\/li\u003e\n\u003cli\u003eReef safe: No; incompatible with reef aquariums due to its burrowing, bulldozing behaviour and adult size\u003c\/li\u003e\n\u003cli\u003eMinimum tank size: 180 gallons (680 litres) is considered the minimum for a single adult; the footprint of the tank matters as much as the volume, as this is a benthic animal that needs extensive floor space to move and forage\u003c\/li\u003e\n\u003cli\u003eA deep, fine sandy substrate is non-negotiable; this species burrows to feed and rest and needs several inches of soft substrate to engage in natural behaviour\u003c\/li\u003e\n\u003cli\u003eJuveniles can adapt to home tanks but grow quickly; a long-term upgrade plan must be in place before purchase\u003c\/li\u003e\n\u003cli\u003eFemales grow significantly larger than males; females can reach up to 60 cm including the telson, while males are roughly one third that size\u003c\/li\u003e\n\u003cli\u003ePump intakes and other suction hazards must be fully screened; this animal will investigate everything on the substrate\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eDiet\u003c\/h3\u003e\n\u003cp\u003eIn the wild, Horseshoe Crabs feed as omnivorous scavengers and substrate hunters, consuming mollusks, polychaete worms, and other sand-dwelling organisms; in captivity they will eat almost any food offered to them.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eFrozen meaty marine foods including mysis, krill, chopped clam, mussel, squid, and shrimp\u003c\/li\u003e\n\u003cli\u003eQuality sinking carnivore pellets\u003c\/li\u003e\n\u003cli\u003eWill scavenge uneaten fish food, detritus, and any organic matter that reaches the substrate\u003c\/li\u003e\n\u003cli\u003eLive or frozen worms are particularly relished and stimulate natural foraging behaviour\u003c\/li\u003e\n\u003cli\u003eFeed every two to three days; target feed by placing food directly onto the substrate in front of the animal\u003c\/li\u003e\n\u003cli\u003eA mature sandbed with a healthy population of microfauna provides important supplemental nutrition between feedings\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eCompatibility and tankmates\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eCompatible with most larger, robust fish that will not harass or nip at it\u003c\/li\u003e\n\u003cli\u003eNot suitable for reef systems with corals, secured aquascaping, or a carefully maintained sandbed community\u003c\/li\u003e\n\u003cli\u003eAvoid aggressive crustacean-targeting species such as large triggers and puffers\u003c\/li\u003e\n\u003cli\u003eLarger peaceful fish including tangs, angelfish, and groupers are generally suitable companions in a large FOWLR system\u003c\/li\u003e\n\u003cli\u003eDo not house with small, delicate bottom-dwelling invertebrates that may be crushed or consumed during foraging\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eHealth and acclimation notes\u003c\/h3\u003e\n\u003cp\u003eHorseshoe Crabs are sensitive to rapid parameter changes, particularly in salinity and dissolved oxygen; slow drip acclimation over at least one hour is essential. The telson tail, which looks alarming, is not a stinger; it is used only for righting itself if it becomes flipped onto its back. If you find one upside down, right it gently by supporting the shell from the sides rather than grabbing the telson. Specimens may occasionally go through prolonged inactive periods that can be mistaken for illness; this is normal behaviour, particularly in cooler periods. A lifespan of 20 or more years is possible in the wild; captive lifespans vary considerably based on the quality of the setup and long-term planning around the animal's size.\u003c\/p\u003e\n\u003ch3\u003eWhat you are buying\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eYou will receive: 1 Atlantic Horseshoe Crab (Limulus polyphemus)\u003c\/li\u003e\n\u003cli\u003eCarapace colour is greenish brown to tan; the telson and leg undersides are pale; colouration varies between individuals\u003c\/li\u003e\n\u003cli\u003eSize at time of sale is juvenile; long-term growth must be planned for before purchase\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eDrip acclimation of at least one hour is strongly recommended. A deep sandy substrate and spacious tank with fully screened pump intakes must be in place before introduction. Copper-based medications must never be used in any system housing this animal. This species is best suited to experienced hobbyists with very large, purpose-planned marine systems.\u003c\/p\u003e","brand":"Little Shop of Coral","offers":[{"title":"Default Title","offer_id":53598890098961,"sku":null,"price":40.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0718\/5196\/6737\/files\/ARROWCRABSTENORHYNCHUSSETICORNI_1.png?v=1779829171","url":"https:\/\/littleshopofcoral.ca\/products\/atlantic-horseshoe-crab-limulus-polyphemus","provider":"Little Shop of Coral","version":"1.0","type":"link"}