Tiger Shrimp: Phyllognatia ceratophthalma

In this episode of relaxation, we would like to focus your attention on a gorgeous little creature that goes by the name Tiger Shrimp, Phyllognatia ceratophthalma. Since its scientific name is of very little help this time, we like to throw in some of its common names: Spiny Tiger Shrimp, Bongo Shrimp, and Horned Bumblebee Shrimp.

This very shy and cryptic shrimp grows up to about 2cm, and likes to hide out in sponges, rubble, algae or broken coral, or in an encrusted mix of all of the above. They look extraordinary, with their beautiful colouration. As they grow older, spikes randomly jutting out from their bodies.

Observe the beauty and details of Tiger Shrimp, Phyllognatia ceratophthalma

Most shrimps are omnivores. However, the diet of the Tiger Shrimp is not totally clear yet. If it behaves similar to other shrimps in the family of Palaemonidae, it feeds on the feet of various Echinoderms, like seastars, brittle stars, urchins and sea cucumbers, for example. Other than using its legs to move around for short distances, the Tiger Shrimp is actually able to swim.

They use a technique named drag swimming, by which they use a cyclic motion where they push water back in a power stroke and return their limb forward in the return or recovery stroke. When they push water directly backwards, it moves their body forward, yet as they return their limbs to the starting position, it pushes the water forward, which in effect will move them back to some degree. This opposing force is called drag, and causes drag swimmers to employ different strategies than lift swimmers. Reducing drag on the return stroke is essential for optimizing efficiency.

Take a closer look before it disappears

As one can admire in this clip, the Tiger Shrimp has beautiful eyes. Each ommatidium (optical unit consisting of photo-receptors and usually multiple lenses) is equipped with a set of plane mirrors. The superposition compound eyes are aligned at right angles, forming a square. This is causing light that enters the eye at an angle to encounter two surfaces of each mirror box rather than only one surface. In this case, the pair of mirrors at right angles acts as a corner reflector, which reflects incoming light rays through 180 degrees, irrespective of the light rays originally came from. This ensures that all parallel rays reach the same focal point and means that the eye as a whole has no single axis, which allows it to operate over a wider angle.

Since so little is known about this beautiful creature, we see it as an ambassador for reef/ocean conservation. Who knows what wonderful abilities and behaviour we might miss out on, when a life that has hardly been studied, disappears from our oceans forever!