Hunting and Feeding: Box Jellyfish (Chironex fleckeri)

The notorious box jellyfish, Chironex fleckeri, is not only among the world’s most dangerous venomous creatures, it is also a very active and formidable predator (Alderslade et al, 1998). The box jellyfish uses the venom in its tentacles not just as a defence mechanism, but also for the express purpose of incapacitating and eating its prey (Marsh and Slack-Smith, 2010). Equipped with as many as 15 tentacles, lined with thousands of stinging cells and armed with over 5,000 specialized barbed nematocysts per arm, the sting from a box jellyfish has the ability to pierce flesh, crustacean cuticle and even the shells of molluscs (Uhlenbroek, 2008). Each cell contains a filament lined with barbs that, when triggered by contact with prey, release explosively and instantly stun and paralyse the target (Marsh and Slack-Smith, 2010). The rapid ejection of this barb is one of the fastest cellular processes ever recorded in nature and turns the barbed filaments inside out with roughly the same energy as firing a small-calibre bullet (Uhlenbroek, 2008).

Belonging to the class Cubozoa, box jellyfish are not true jellyfish but are closely related (Marsh and Slack-Smith, 2010). They are capable of moving at speeds up to 7.2kph by using a form of jet propulsion and are equipped with 24 eyes arranged in four groups of six on each side of the body (Marsh and Slack-Smith, 2010). While most of these eyes are simple organs capable of responding only to light and dark, one pair in each cluster has the ability to form images and may guide the jellyfish to its prey (Uhlenbroek, 2008).

Whilst the box jellyfish usually preys on small fish and crustaceans, they pose a significant threat to humans with its excruciatingly painful stings causing heart failure and shock often leading to drowning (Uhlenbroek, 2008).

Reference:

Alderslade, P., Bloom, D.A. & Burnett, J.W. (1998). Partial purification of box jellyfish (Chironex fleckeri) nematocyst venom isolated at the beachside. Toxicon, 36(8), 1075-1085.

Marsh, L.M. & Slack-Smith, S. (2010). Field Guide to Sea Stingers and Other Venomous and Poisonous Marine Invertebrates. Western Australia, AUS: Western Australian Museum.

Uhlenbroek, C. (2008). Animal Life. Penguin Group, UK.