Biological signals based on color patterns are well known, but some animals communicate by producing patterns of polarized light. Known biological polarizers are all based on physical interactions with light such as birefringence, differential reflection or scattering. We describe a novel biological polarizer in a marine crustacean based on linear dichroism of a carotenoid molecule. The red-col...

Within the tropical and subtropical oceans, tuna forage opportunistically on a wide variety of prey. However, little is known about the trophic ecology of the smallest size classes which play an important role in stock assessments and fisheries management. The foraging behavior of yellowfin tuna, Thunnus albacares (23.5–154.0 cm FL), collected from nearshore Fish Aggregating Devices (FADs) arou...

1. Regional specialization within the triple compound eyes of the gonodactyloid stomatopod Conodactylus oerstedii (Hansen) was studied by examining how ocular tracking of a small target was affected after occluding vision in particular ommatidial regions with black enamel paint. 2. Complete occlusion of one eye did not prevent the other eye from tracking, indicating that the two eyes act somewh...

Neurons in the heart ganglion of the mantis shrimp (a stomatopod crustacean) are functionally tightly linked together. The extracellular action potential from the whole trunk very often shows a complex form, but the response is all-or-none to the applied stimulus, indicating that the excitation in one neuron spreads very rapidly to all others. Application of isotonic MgCl(2) solution or repetit...

The pacemaker neurons of the Squilla heart ganglion are innervated from the CNS through three pairs of extrinsic nerves. One of them, the alpha-nerve, is inhibitory to the heart beat. The effect of alpha-nerve stimulation on the pacemaker potential was examined with intracellular electrodes. Without extrinsic nerve stimulation the membrane potential of the pacemaker cell fluctuated spontaneousl...