Cookiecutter Shark
Isistius brasiliensis
- Diet
- A facultative ectoparasite that removes tissue from larger animals but also eats smaller prey whole.
- Size
- Males: Up to 42 cm; Females: Up to 56 cm
- Range
- Tropical and warm-temperate oceanic basins worldwide, especially between 20°N and 20°S.
- Habitat
- Open ocean, frequently near islands; found from the upper water column to depths of 3.7 km.
- Activity
- Conducts a daily vertical migration: it approaches the surface around dusk and descends with dawn. During the day it is usually found at 1–3.7 km depth; at night it generally remains below 85 m.
- Reproduction
- Aplacental viviparous; embryos are nourished by yolk. Females have two functional uteri and produce litters of 6–12 pups.
- Conservation
- Least Concern (IUCN assessment, 2018)
- Finding food
- Its name comes from the neat, round plugs of flesh it removes from much larger animals. The resulting crater-like wounds average 5 cm across and 7 cm deep.
- Camouflage
- Light-producing organs called photophores cover almost the entire underside and create a green glow. This counter-illumination can make the shark’s silhouette harder to see from below.
- Camouflage
- A dark collar around the throat does not glow. It may resemble the silhouette of a small fish and act as a lure, although this proposed function is not certain.
- Finding food
- The shark grips prey with suction from its lips and mouth, anchors with its upper teeth, then uses its broad lower teeth to cut a circular plug while twisting its body.
- Life cycles
- It regularly replaces its teeth by shedding the lower teeth in whole rows. Old tooth sets are swallowed, allowing the shark to recycle their calcium.
Facts
- Its name comes from the neat, round plugs of flesh it removes from much larger animals. The resulting crater-like wounds average 5 cm across and 7 cm deep.
- Light-producing organs called photophores cover almost the entire underside and create a green glow. This counter-illumination can make the shark’s silhouette harder to see from below.
- A dark collar around the throat does not glow. It may resemble the silhouette of a small fish and act as a lure, although this proposed function is not certain.
- The shark grips prey with suction from its lips and mouth, anchors with its upper teeth, then uses its broad lower teeth to cut a circular plug while twisting its body.
- It regularly replaces its teeth by shedding the lower teeth in whole rows. Old tooth sets are swallowed, allowing the shark to recycle their calcium.
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