Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons (neurones). In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.
Mantis shrimp are carnivorous marine crustaceans of the order Stomatopoda. Stomatopods branched off from other members of the class Malacostraca around 340 million years ago. Mantis shrimp typically grow to around 10 cm (3.9 in) in length, while a few can reach up to 38 cm (15 in). A mantis shrimp's carapace covers only the rear part of the head and the first four segments of the thorax. Varieties range in colour from shades of brown to vivid colours, with more than 520 species of mantis shrimp known. They are among the most important predators in many shallow, tropical and subtropical marine habitats. However, despite being common, they are poorly understood, as many species spend most of their lives sheltering in burrows and holes.
Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from 1 to 340 millimetres and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far described. They are mostly marine animals, but are found in almost all aquatic environments. Some 1,900 species live in fresh water, and the order also includes the terrestrial sandhoppers such as Talitrus saltator and Arcitalitrus sylvaticus.
The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word pelagic is derived from Ancient Greek πέλαγος (pélagos) 'open sea'. The pelagic zone can be thought of as an imaginary cylinder or water column between the surface of the sea and the bottom. Conditions in the water column change with depth: pressure increases; temperature and light decrease; salinity, oxygen, micronutrients all change. Somewhat analogous to stratification in the Earth's atmosphere, but depending on how deep the water is, the water column can be divided vertically into up to five different layers.
Aequorea victoria, also sometimes called the crystal jelly, is a bioluminescent hydrozoan jellyfish, or hydromedusa, that is found off the west coast of North America.
Epimeriidae is a family of relatively large amphipods found in cold oceans around the world.
The Hyperiidea are a suborder of amphipods, small aquatic crustaceans. Unlike the other suborders of Amphipoda, hyperiids are exclusively marine and do not occur in fresh water. Hyperiids are distinguished by their large eyes and planktonic habitat. Most species of hyperiids are parasites or predators of salps and jellyfish in the plankton, although Themisto gaudichaudii and a few relatives are free-swimming predators of copepods and other small planktonic animals.
Themisto gaudichaudii is an amphipod crustacean of the suborder Hyperiidea.
Phronima sedentaria is a species of amphipod crustaceans found in oceans at a depth of up to 1 km (0.6 mi). They are large in size relative to other members of the family Phronimidae. Individuals may be found inside barrel-like homes, created most commonly from the tunics of select species of tunicate, where they rear their young. P. sedentaria is known to employ multiple feeding strategies and other interesting behaviors, including daily vertical migration. The species is also known by the more common names “pram bug” and “barrel shrimp.”
Alicella gigantea is the largest species of amphipod ever observed, with some individuals reaching up to 34 centimetres (13 in) long. The average length of A. gigantea ranges from 72.5 to 141.0 millimeters, and its weight ranges from 4.2 to 45 grams. Comparatively to other amphipods, the A. gigantea grows at a much faster rate. Formerly included in the family Lysianassidae, a new family, Alicellidae, was erected in 2008 for Alicella and five related genera. The species lives only at great depths; the first specimens were collected at the end of the 19th century from the Madeira Abyssal Plain, and subsequent specimens have been found in other abyssal plains of both the Atlantic and Pacific Oceans, as well as from the Kermadec Trench in the southwest Pacific. One specimen was found in the stomach of a black-footed albatross, but is thought to have been dead before it was eaten.
Gonodactylus smithii, also known as the purple spot mantis shrimp or Smith's mantis shrimp, is a species of the smasher type of mantis shrimp. G. smithii are the first animals discovered to be capable of dynamic polarization vision. They are identified by their distinctive meral spots ranging from maroon to purple with a white ring, though those that inhabit depths below 10 meters tend to be colored maroon. They also have raptorial dactyles, specialized forelimbs that are pigmented green and red, and antennal scales that are yellow.
Underwater camouflage is the set of methods of achieving crypsis—avoidance of observation—that allows otherwise visible aquatic organisms to remain unnoticed by other organisms such as predators or prey.
Parhyale hawaiensis is an amphipod crustacean species that is used in developmental and genetic analyses. It is categorized as an emerging model organism as the main biological techniques necessary for the study of an organism have been established.
Maritrema subdolum is a species of parasitic fluke found in the Wadden Sea. It is related to the New Zealand species Maritrema novaezealandensis, and like its New Zealand relative, Maritrema subdolum infects local amphipods, in this case, Corophium volutator and Corophium arenarium. The cercariae of M. subdolum emerge from the first intermediate host, a gastropod of the genus Hydrobia for example, and seek out the next host, a crustacean. There the cercariae develop into metacercariae and form metacercarial cysts of different sizes.
Caprella mutica, commonly known as the Japanese skeleton shrimp, is a species of skeleton shrimp. They are relatively large caprellids, reaching a maximum length of 50 mm (2.0 in). They are sexually dimorphic, with the males usually being much larger than the females. They are characterized by their "hairy" first and second thoracic segments and the rows of spines on their bodies. Body color ranges from green to red to blue, depending on the environment. They are omnivorous highly adaptable opportunistic feeders. In turn, they provide a valuable food source for fish, crabs, and other larger predators. They are usually found in dense colonies attached to submerged man-made structures, floating seaweed, and other organisms.
Eurythenes is a genus of marine amphipods in the family Eurytheneidae.
Eurythenes plasticus is a species of amphipod of the genus Eurythenes, first described in 2020. It was named in reference to the PET plastic found in its stomach, after researchers wanted to highlight the impact of plastic pollution.
Neobirsteiniamysis is a mysid crustacean genus of the subfamily Boreomysinae of the family Mysidae. Some of the largest mysids. Exclusively deep water. Cosmopolitan. 2 species.
Neobirsteiniamysis inermis is a deepwater mysid crustacean species of the genus Neobirsteiniamysis. One of the largest and the only known mysid, distributed in both polar regions.
A micronekton is a group of organisms of 2 to 20 cm in size which are able to swim independently of ocean currents. The word 'nekton' is derived from the Greek νήκτον, translit. nekton, meaning "to swim", and was coined by Ernst Haeckel in 1890.
Specimen in side view
Specimen in dorsal view
Underside view
