Splendors of the Sea
Oceans cover over 70% of the earth's surface, making them the largest and most diverse of the world's ecosystems. Scientists have divided the ocean into five main layers: epipelagic, mesopelagic, bathypelagic, abyssopelagic, and lastly hadapelagic. These layers, known as "zones," extend from the surface to extreme depths past 20,000 feet. Though most organisms live in the epipelagic zone (because this is the layer where most of the visible light exists), marine organisms can be found in all levels of the ocean. The deepest known point is located in the Mariana Trench off the coast of Japan at 35,797 feet. The temperature at this depth is just above freezing, and the pressure is an astonishing eight tons per square inch (the weight of 48 Boeing 474 jets). In spite of the temperature and pressure, life can still thrive at these depths.
As a society, we incorporate the ocean in our everyday lives: from transportation - to the use of its vast resources - to its recreational aspects. The Rosenberg Library had an assortment of shells and organisms on display to represent a variety of the more local species. Many of the items were found along the Galveston beaches.
Sand dollars are flat, round marine animals that are related to sea urchins and sea stars. The bodies of these animals consist of a set of five pores arranged in a petal pattern. The pores are used to move sea water into the internal water-vascular system, allowing the creature to move. Once sand dollars die and wash up on the beach, they are usually missing their spines and velvety covering, and their color has been bleached out by the sun.
Sea urchins are small, globular creatures with protective spines. Their colors range from black and brown to purple, green, and red. Urchins move slowly through the water as they feed on algae. These unusual sea animals are considered a culinary delicacy in some parts of the world.
Sea beans are seeds and fruits from coastal plants that make their way into the ocean and drift along with ocean currents. They can be found washed ashore in all parts of the world, particularly after high tides during hurricane season. Some sea beans are used for medicinal purposes and can found in nutritional supplements.
Reef-building corals are actually made up of two different living organisms — an animal and a plant that lives inside the animal. The animal portion is a simple polyp with a circle of tentacles surrounding a central mouth. Hundreds of thousands of interconnected polyps form a reef. The plant portion is single cell of algae that lives inside the polyp. The polyp provides a home for the algae and also provides the nitrogen and carbon dioxide needed for photosynthesis. In exchange, the algae uses photosynthesis to produce food for the animal.
Sea Stars (Starfish)
There are approximately 2,000 species of sea star living the world’s oceans. Though most species have five arms, some types of star fish can have up to forty arms. Their bony, calcified skin protects them from most predators, and many are brightly colored to scare off potential attackers. Sea stars are well known for their ability to regenerate lost limbs. Some sea stars require an intact central body in order to regenerate; however, a few species can grow an entirely new sea star from just a portion of a severed limb. Most sea stars also have the remarkable ability to consume prey outside their bodies by using their cupped tube feet to pry open clams and oysters. They consume their prey with a sack-like cardiac stomach.
Sawfish are a family of marine animals related to sharks and rays. Their most striking feature is their saw-like snout, called the rostrum. The rostrum works like a metal detector as the sawfish hovers over the ocean floor looking for hidden food. It is also used as a digging tool to unearth buried crustaceans. The sawfish catches its prey by waiting for a fish to swim by before it slashes at it with its saw, usually stunning or injuring the prey.
Sawfish are found in tropical and sub-tropical areas around Africa, Australia, and the Caribbean. They can be found in both fresh and salt water. All species of sawfish are considered critically endangered.
Seahorses are named for their equine appearance. Although they are fish, they do not have scales; rather they have a thin skin that stretches over a series of bony plates throughout their body. There are about 35 known species of seahorses. Their size depends on the species but can range anywhere from ¼ inch to over a foot. They are found in most of the world’s temperate and tropical coastal waters and in some of the world’s most threatened habitats: sea grasses, mangroves, coral reefs and estuaries. Seahorses are rare in that they are monogamous creatures, and it is the male who becomes pregnant when the female deposits eggs into his pouch. Each seahorse pregnancy lasts between 2 and 4 weeks. Males give birth to as few as 5 but as many as 2,000 “fry” at a time. Once the male gives birth, he usually becomes pregnant again right away.