MARINE MOBILE HOMES
Marine Mobile Homes, acrylic on canvas, 2022. 18" X 24"
Several marine animals have hard shells as a means of protection. These shells are usually made of calcium carbonate, which is the same material that makes up the bones of most animals. The shells were once thought to be the "mobile homes" of these animals where they could hide inside, but these shells are actually more than what they seem.
A sea turtle's shell is made of bone and is covered with a hard layer of keratin, which is a material which also makes up the hair and fingernails of mammals. The turtle shell is made of two pieces, the top layer which is called the carapace, and the bottom part is called a plastron. They are fused on each side by a structure called a bridge. The carapace is made of smaller individual pieces called scutes, which are similar to scales.
Hitching a ride on the turtle's back in the painting is a periwinkle snail, which is feeding on parasites on the turtle's shell. The common periwinkle (Littorina littorea) is native to the rocky shores lining the northeastern Atlantic Ocean. Its shell comes in various colors from light yellow to dark brown.
The shell of the chambered nautilus (Nautilus pompilius) is often used as a reference point for the golden spiral, in which its growth factor is equal to the mathematical golden ratio. The shell contains several pockets of air to serve as a buoy to keep it afloat. The nautilus controls its buoyancy by controlling the amount of liquid inside these air pockets, similar to ballast tanks in a submarine. The chambered nautilus inhabits different segments of the shell throughout its growth, continuously growing new, larger "cells" into which it moves its internal organs as it grows in maturity.
The paper nautilus, also known as the greater argonaut (Argonauta argo), is a cousin of the nautilus, but is more closely related to the octopus. The female paper nautilus secretes a paper-thin egg case which covers the animal much like the way a nautilus lives in its shell, hence the name. However, the egg case lacks the gas-filled chambers present in nautilus shells, making it not a true shell but instead a unique evolutionary innovation. Paper nautiluses are present in tropical and subtropical waters worldwide.
The onyx cowrie (Erronea onyx, left) is a type of seashell known as a cowrie which shells had been historically used as money and jewelry. A cowrie's shell is usually smooth, shiny and egg-shaped. The round side of the shell is called the dorsal face while the flat side is the ventral face. The dorsal face of the onyx cowrie bears a striking resemblance to the onyx gemstone, which led to its name.
The marmorated, or marbled cone snail (Conus marmoreus, front) is a cone snail with a distinctive, reticulated color pattern that ranges from black with white dots, to orange with white patterns, so arranged as to expose the white markings in rounded, triangular large spots. This snail is venomous, like all cone snails, and uses said venom to hunt small prey.
The giant clam (Tridacna gigas, right) is the largest living bivalve mollusk. The giant clam lives in flat coral sand or broken coral and can be found at depths of as much as 20 m (66 feet). The clam's mantle tissues act as a habitat for symbiotic single-celled algae called zooxanthellae from which the adult clams get most of their nutrition. By day, the clam opens its shell and extends its mantle tissue so that the algae receive the sunlight they need to carry out photosynthesis.
The hermit crab is a crustacean that has adapted to live in empty shells to protect their fragile exoskeletons. There are over 800 species of hermit crabs. As a hermit crab grows in size, it must find a larger shell and leave the previous one vacant.
The lamp shell (Lingula anatina, top right) is a member of a group of mollusks called brachiopods. They had hinged hard shells called valves which are arranged on the top and bottom, unlike the left and right arrangement in bivalves. Lamp shells only live in marine habitats. The soft part of the body protruding from seashells is called a "foot".
The northern or Pinto abalone (Haliotis kamtschatkana, bottom right) is a species of abalone, a family of ear-shaped marine snails known for their popularity in the seafood industry. It ranged across northern North America, where it was harvested commercially until the middle 1990s. Due to overharvesting, the northern abalone became a threatened species in its native range. An abalone's shell has a row of holes which it uses for breathing, reproduction and waste removal. The holes themselves change over the course of the abalone's life, either closing up or being made bigger.
The limpet (bottom middle) is an aquatic snail that has a conical shell shape (patelliform) and a strong, muscular foot. Many species of limpets have historically been used, or are still used, by humans and other animals for food.
The chiton (bottom right) is an armored, slug-like gastropod which belongs to the family Polyplacophora. There are around 940 species of chitons. Chitons are also sometimes known as sea cradles or coat-of-mail shells. They have a shell composed of eight overlapping shell plates or valves which are well-articulated, enabling the animals to move across uneven surfaces and curl themselves up into a ball. The shell plates are surrounded by a skirt known as a girdle.
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