Limulus polyphemus (Atlantic Horseshoe Crab) | Ancient Sand-Sifting Marine Invertebrate

The Limulus polyphemus, commonly known as the Atlantic Horseshoe Crab, is a fascinating marine species that has existed for over 450 million years, making it a true living fossil. Despite its name, it is more closely related to arachnids and scorpions than actual crabs. As a natural detritivore, it plays a crucial role in marine ecosystems by sifting through the substrate in search of organic matter, helping to maintain a clean and balanced aquarium. Best suited for experienced aquarists, it requires a large tank with a deep sand bed for optimal care.

Key Benefits:

✔ Unique living fossil – A species of scientific and educational interest.

✔ Helps clean the substrate – Digs through sand to consume organic matter.

✔ Fascinating behavior – Nocturnal and constantly exploring the tank floor.

✔ Hardy and resilient – Can tolerate parameter fluctuations if properly acclimated.

✔ Reef-safe with caution – Non-aggressive but may overturn loosely placed corals.

Technical Specifications:

• Scientific Name: Limulus polyphemus

• Average Adult Size: 15-60 cm (depending on age and conditions)

• Origin: North American Atlantic Coast, Gulf of Mexico

• Ideal Temperature: 20-26°C

• Salinity: 1.023 – 1.025

• pH: 8.1 – 8.4

• Lighting: Low to moderate (nocturnal species)

• Water Flow: Moderate to strong (prefers well-oxygenated substrate)

Care Instructions & Recommendations:

1️⃣ Compatibility: Best suited for large tanks (400L+) with a deep sandy substrate.

2️⃣ Feeding: Detritivore, consumes worms, crustaceans, organic waste, and meaty foods.

3️⃣ Behavior: Nocturnal burrower, mostly active at night.

4️⃣ Acclimation: Drip acclimation recommended for stress-free adaptation.

5️⃣ Maintenance: Requires at least a 10 cm deep sand bed for burrowing and exploration.