Late afternoon alpenglow on Mt. Werner in Steamboat Springs, CO.
Early morning fall sunrise over the Yampa River in Steamboat Springs, Colorado.
During the Hot Air Balloon Rodeo, the Colorado balloon soars high above the Yampa Valley.
© CJ Berg 2009
The red sea urchin (Mesocentrotus franciscanus) is a sea urchin found in the northeastern Pacific Ocean from Alaska to Baja California. It lives in shallow waters from the low-tide line to greater than 100 m (330 ft) deep, and is typically found on rocky shores sheltered from extreme wave action.
A sea urchin's spherical body is completely covered by sharp spines. These spines grow on a hard shell called the "test", which encloses the animal. It can vary in color from red to dark burgundy. Rarely, albino specimens are found. It has a mouth located on its underside, which is surrounded by five teeth. During larval development, the body of a sea urchin transitions from bilateral to radial symmetry.
This bilaterally symmetrical larva, called an echinopluteus, subsequently develops a type of pentaradiate symmetry that characterises echinoderms. It crawls very slowly over the sea bottom using its spines as stilts, with the help of its tube feet. Scattered among its spines are rows of tiny tube feet with suckers that help it to move and stick to the sea floor.
Most nudibranchs sport bright colors — sea lemons are deep yellow to burnt orange. Black spots mingle with protruding bumps (tubercles) on the sea lemon's back. Fleshy antennae (sensory organs) and a rosette of gills protrude from the back of a sea lemon's slim, flat body.
A sea lemon, like all nudibranchs, is hermaphroditic and can produce both sperm and eggs. Since nudibranchs live only about one year, the ability to mate with any other nudibranch increases their chances of reproducing.
Circular, light yellow ribbons contain as many as 2,000,000 eggs; less than 1% of the resulting larvae survive. In Monterey Bay, the spawning season is from November to March.
Sea lemons breathe through the rosette of gills on their back. Nudibranchs that have this arrangement of gills are in a family called dorids.
Because the neurons of sea lemons are larger and easier to access than human neurons, researchers find sea lemons useful in their studies of nerve cells. In addition, the abundance of sea lemons makes their collection for research feasible.
A nudibranch's color often matches the color of the sponge it eats.
Sea anemones are a group of marine, predatory animals of the order Actiniaria. They are named after the anemone, a terrestrial flowering plant, because of the colourful appearance of many. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Hexacorallia. As cnidarians, sea anemones are related to corals, jellyfish, tube-dwelling anemones, and Hydra. Unlike jellyfish, sea anemones do not have a medusa stage in their life cycle.
A typical sea anemone is a single polyp attached to a hard surface by its base, but some species live in soft sediment and a few float near the surface of the water. The polyp has a columnar trunk topped by an oral disc with a ring of tentacles and a central mouth. The tentacles can be retracted inside the body cavity or expanded to catch passing prey. They are armed with cnidocytes (stinging cells). In many species, additional nourishment comes from a symbiotic relationship with single-celled dinoflagellates, zooxanthellae or with green algae, zoochlorellae, that live within the cells. Some species of sea anemone live in association with hermit crabs, small fish or other animals to their mutual benefit.
Sea anemones breed by liberating sperm and eggs through the mouth into the sea. The resulting fertilized eggs develop into planula larvae which, after being planktonic for a while, settle on the seabed and develop directly into juvenile polyps. Sea anemones also breed asexually, by breaking in half or into smaller pieces which regenerate into polyps. Sea anemones are sometimes kept in reef aquariums; the global trade in marine ornamentals for this purpose is expanding and threatens sea anemone populations in some localities, as the trade depends on collection from the wild.