Summarise the wikipedia article about Australian box jellyfish and form interesting key points for a school presentation in form of a short list:

Chironex fleckeri is the largest of the cubozoans (collectively called box jellyfish), many of which may carry similarly toxic venom. Its bell usually reaches about 16 cm in diameter but can grow up to 35 cm. From each of the four corners of the bell trails a cluster of 15 tentacles. The pale blue bell has faint markings; viewed from certain angles, it bears a somewhat eerie resemblance to a human head or skull. Since it is virtually transparent, the creature is nearly impossible to see in its habitat, posing significant danger to swimmers.
When the jellyfish are swimming, the tentacles contract so they are about 150 mm (5.9 in) long and about 5 mm (0.20 in) in diameter; when they are hunting, the tentacles are thinner and extend to about 3 m (9.8 ft) long. The tentacles are covered with a high concentration of stinging cells called cnidocytes, which are activated by pressure and a chemical trigger; they react to proteinous chemicals. Box jellyfish are day hunters; at night they are seen resting on the ocean floor.
In common with other box jellyfish, NAME_1. fleckeri has four eye-clusters with 24 eyes. Some of these eyes seem capable of forming images, but whether they exhibit any object recognition or object tracking is debated; it is also unknown how they process information from their sense of touch and eye-like light-detecting structures due to their lack of a central nervous system. They are attracted to light of different colors (white, red, orange, yellow, green and blue), but blue light seems to elicit a feeding behavior, as it slows down their pulsation rate and makes them stream out their tentacles. Black objects, on the other hand, cause them to move away.
Chironex fleckeri lives on a diet of prawns and small fish and are prey to turtles, whose thick skin is impenetrable to the cnidocytes of the jellyfish. Do not include the following keywords: color, point, contract, light
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