Ultraviolet filters in stomatopod crustaceans: diversity, ecology and evolution.

Stomatopod crustaceans employ unique ultraviolet (UV) optical filters in order to tune the spectral sensitivities of their UV-sensitive photoreceptors. In the stomatopod species Neogonodactylus oerstedii, we previously found four filter types, produced by five distinct mycosporine-like amino acid pigments in the crystalline cones of their specialized midband ommatidial facets. This UV-spectral tuning array produces receptors with at least six distinct spectral sensitivities, despite expressing only two visual pigments. Here, we present a broad survey of these UV filters across the stomatopod order, examining their spectral absorption properties in 21 species from seven families in four superfamilies. We found that UV filters are present in three of the four superfamilies, and evolutionary character reconstruction implies that at least one class of UV filter was present in the ancestor of all modern stomatopods. Additionally, postlarval stomatopods were observed to produce the UV filters simultaneously alongside development of the adult eye. The absorbance properties of the filters are consistent within a species; however, between species we found a great deal of diversity, both in the number of filters and in their spectral absorbance characteristics. This diversity correlates with the habitat depth ranges of these species, suggesting that species living in shallow, UV-rich environments may tune their UV spectral sensitivities more aggressively. We also found additional, previously unrecognized UV filter types in the crystalline cones of the peripheral eye regions of some species, indicating the possibility for even greater stomatopod visual complexity than previously thought.

Bok MJ ，Porter ML ，Cronin TW 《-》

Biological sunscreens tune polychromatic ultraviolet vision in mantis shrimp.

Stomatopod crustaceans, or mantis shrimp, are renowned for their complex visual systems. Their array of 16 types of photoreceptors provides complex color reception, as well as linear and circular polarization sensitivity [1-6]. The least-understood components of their retina are the UV receptors, of which there are up to six distinct, narrowly tuned spectral types [4]. Here we show that in the stomatopod species Neogonodactylus oerstedii, this set of receptors is based on only two visual pigments. Surprisingly, five of the six UV receptor types contain the same visual pigment. The various UV receptors are spectrally tuned by a novel set of four short- and long-pass UV-specific optical filters in the overlying crystalline cones. These filters are composed of various mycosporine-like amino acid (MAA) pigments. Commonly referred to as "nature's sunscreens," MAAs are usually employed for UV photoprotection [7, 8], but mantis shrimp uniquely incorporate them into powerful spectral tuning filters, extending and diversifying their preeminently elaborate photoreceptive arsenal.

Bok MJ ，Porter ML ，Place AR ，Cronin TW ... -  《-》

Evolution of anatomical and physiological specialization in the compound eyes of stomatopod crustaceans.

Porter ML ，Zhang Y ，Desai S ，Caldwell RL ，Cronin TW ... -  《-》

Tuning of photoreceptor function in three mantis shrimp species that inhabit a range of depths. II. Filter pigments.

Cronin TW ，Caldwell RL 《JOURNAL OF COMPARATIVE PHYSIOLOGY A-NEUROETHOLOGY SENSORY NEURAL AND BEHAVIORAL PHYSIOLOGY》

Tuning of photoreceptor function in three mantis shrimp species that inhabit a range of depths. I. Visual pigments.

Cronin TW ，Caldwell RL ，Erdmann MV 《JOURNAL OF COMPARATIVE PHYSIOLOGY A-NEUROETHOLOGY SENSORY NEURAL AND BEHAVIORAL PHYSIOLOGY》