Visual Field Clutter – Learn About Apposition Compound Eyes



The Crustacea are a diverse, yet beautiful group of crustaceans. With an average eye length of two and a half inches and a wide range of colors from bright yellow to dark browns, crustaceans can be a good choice for your aquarium. Their adaptability, easy care, and a stunning variety mean that crustacea are ideal for just about any aquarium situation, making them a great option for new aquarists.


The crustacean group includes a number of intriguingly diverse creatures, including the well-known small crustaceans such as the false albino glistening worm, the scarlet cleaner shrimp, and the small legged crayfish called the rocker head crab. They are also host to many parasitic crustaceans, including some of the most familiar members of the crustacean group such as the whip shrimp, the black soldier shrimp, the carpet shrimp, and the boxer shrimp. They are also home to several types of worms and other crustaceans, such as the cuttlefish and the surgeonfish. All of these members of the crustacean share a common evolutionary pathway that stretches back through multiple relationships with crustaceans, with some of the examples of this progression being recognizable through similarities in their morphological diversity.

Major groupings of crustaceans

The major groupings of crustaceans all belong to a single ancestral group, which is also referred to as the Prototheria. This includes such crustaceans as the sea and the wolflip. Within this overall ancestry, there are several minor subgroups that each represents an evolved branch of the main ancestral branch. For example, there is the Triassic or ‘early’ crustacean, which includes such crustaceans as the cuttlefish, the rockerhead crab, the Harlequin shrimp, and the velvet shrimp. Subsequently, there are several paraphysodic or ‘post-paleozoic’ crustaceans such as the eustachian and the Ordovician crustaceans.


The crustaceans that are closest to our own species belong to the crustacea, which are more closely related to both the snails and the clams than they are to either the snails or the clams. Within crustaceans, there are two major classes, and these are the Neoplosaurus (neither a reptile nor a mollusk) and the Ornithischia. Neoplosaurs are very closely related to modern-day crabs and shrimp, while the Ornithischia are much less closely related, comprising mostly of mollusks and snails. All of the crustaceans in this group are basal members of the Cladinae, which are a class of multicellular organisms. This implies that the crustaceans represent a part of a cluster that includes the various crustaceans that are basal members of the Cladinae.


As for the group of crustaceans that share their general habitat with other crustaceans, we find three: the cephalopods, the cuttlefish mantis shrimp and the crustaceans that are most closely related to the crustaceans but have evolved separately. In fact, there are many speculations regarding how these crustaceans and mantis shrimps have differentiated from each other through their eye evolution. For instance, crustaceans may have been able to survive because their predators did not have an eye problem, and the evolution of mantis shrimp might have been the result of the mantis shrimp eating its own kind (not realizing it), and the development of crustaceans might have occurred at the same time as the evolution of mantis shrimp.


When talking about the crustacea, we can mention three primary categories of specimens, namely the cephalopod, the crustaceans, and the mollusks. These groups are further divided into a number of subclasses and numerous types of specimens. Each classification has different characteristics and uses the exact optical principles to create the optical illusions. We have mentioned some examples:

Widely used examples

For the crustaceans, the most widely used examples are those which live in benthic or muddy areas. For example, crustaceans that dwell in muddy bottoms or in dark benthic areas can be used as a base for the optical designs. Many of these crabs are found using a combination of reflective and non-reflective surfaces to make the optical illusions. For example, the decapods (left above) use reflective surfaces and the right one (right above) uses non-reflective surfaces to reflect light back to themselves.


Meanwhile, the crustaceans that do not belong to crustaceans and mollusks are not left out. These are some examples for the Apposition Compound Eyes (ACOs) in mollusks and crustaceans. These animals have small eyes without any stomatopod components that allow them to move with the visual field and not depend on its direction of movement. In fact, they can move in a complex fashion and “see” the scene around them, this is a bit different from the crustaceans.

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