The horseshoe crab: a keystone species Miss Robertson 7R

Horseshoe crab

habitat The Horseshoe Crab can be found living in warm, shallow coastal waters They prefer sandy or muddy ocean bottoms Horseshoe Crabs can be mainly found on the Eastern seaboard of the United States; down the Gulf Coast, and along the east coast of Mexico Other varieties can be found along the coasts of southeastern Asia The emerge from the ocean floor to breed on the beaches during the late spring

Food web Sanderling Sea turtle Bass Red Knot Horseshoe Crab Clams Worms Plankton

Keystone species The Horseshoe Crab is an organism that is depended upon by many other organisms, making it a keystone species Over 30 species of shorebirds & migratory birds, such as the Red Knot, the Sanderling, the Ruddy Turnstone and the Semipalmated Sandpiper, use horseshoe crab eggs as an important part of their diet The high protein content of the eggs provides fuel their long migratory journeys Many species of fish, such as the bass, also depend on Horseshoe Crab eggs and newly hatched Horseshoe Crabs for their diet Essential part of oceanic food web

Disappearance Approximately 75% of the Horseshoe Crabs in Delaware Bay have disappeared since the early 1990s They are used largely as bait for the Eel and Conk fishing industries Horseshoe Crabs are also used by the biomedical industry as their blood contains a unique chemical that detects infection Use the blood to test IV drugs and medications to ensure their safety in human patients Horseshoe Crabs are losing their habitat to coastal development. This means they have no where to lay their eggs

consequences Disappearance of shorebirds and migratory birds, such as the Red Knot Red Knot populations have decreased by 70% in the last 5 years They are now at a critical number – one disaster could cause their extinction Change food webs in both Chile and the Arctic where the Red Knot serves a food for other predatory animals such as foxes Loss of an important biomedical product IV drugs will have to be tested in other, slower, less effective ways Hurt human health Loss of bait for fisherman Loss of incomes and livelihoods

REFERENCES Agricultural, Fisheries and Conservation Department. https://www.afcd.gov.hk/english/conservation/con_mar/con_mar_hor/con_mar_hor_life/images/ hor_draw9.jpg. Accessed Nov. 9, 2015 Galathea 3. http://www.galathea3.dk/dk/Menu/Forskning/Dolkhaler/home. Accessed Nov. 9, 2015 Horseshoe Crab. https://www.nwf.org/Wildlife/Wildlife-Library/Invertebrates/Horseshoe- Crab.aspx. Accessed Nov. 9, 2015 Integration and Application Network. http://ian.umces.edu/imagelibrary/displayimage-76- 2233.html. Accessed Nov. 9, 2015 View from the Cape. http://cmboviewfromthecape.blogspot.ca/2010_05_01_archive.html. Accessed Nov. 9, 2015 The Horseshoe Crab as a Keystone Species. http://cumauriceriver.org/downjersey/natural/n- lesson13.html. Accessed Nov. 9, 2015 Crash: A Tale of Two Species. NATURE.