Aquarium News Archive
Ultrasonic Fish: Territorial male kelp greenlings often chase away other male greenlings, but exactly how far an individual roams is a question UC graduate student Jan Freiwald hopes to answer. By surgically implanting small one-inch-long acoustic transmitters in his fish, Freiwald is able to remotely track 50 kelp greenlings as they fin over a shallow reef off Lover’s Point in nearby Pacific Grove.
“Each acoustic transmitter emits a unique short-range ultrasonic signal identifying the fish ccarrying the transmitter,” explains Freiwald. Three signal receivers anchored in his study site “listen” for these signals as they repeat every five minutes and transmit any information received to a computer onshore. A process called triangulation uses slight differences between the arrival time of an ultrasonic signal, as recorded by each receiver, to calculate the exact location of Freiwald’s greenlings on the reef. “I didn’t expect they would have such small little areas for years” Freiwald says about his fish. Preliminary findings suggest both adult and young fish of both sexes stay within an area of only several hundred square meters (about the size of a little league baseball diamond) for years!
Ever curious, Freiwald is taking his research further, temporarily
removing some these fish from his study site to determine if
the ranges of the remaining kelp greenlings is affected by the
overall reduction of this species in an area. In the meantime,
one of Freiwald’s kelp greenlings has been given a temporary
home in our Rocky Reef exhibit for you to see.
Nudibranchs: A favorite to many who love the sea, those colorful, fanciful nudibranchs (sea slugs) are back to add splash of color this summer! Common names like the “sea lemon” or “Spanish shawl” and “ Hopkins ’ rose” allude to their brilliant pigmentation—a veritable rainbow of one-footed wonders.
To defend themselves against predators, some nudibranchs produce foul tastes or odors, while others harbor toxic chemicals. Other species have developed the ability to ingest their favorite cnidarian prey (like anemones and hydroids) armed with stinging cells. Amazingly, nudibranchs are able to pass the stinging cells untriggered through their digestive tracts, then incorporate them into their own tissues as defense weapons.
Although some nudibranchs are easily distinguished from each other, others look alike to the untrained eye. During your next visit this summer we’ll show you a few characteristics scientists look for to help them distinguish between similar looking species of slugs so you can tell them apart yourself.
(July 2005) Brittle stars , a type of echinoderm, are aptly named for their long, slender arms that are easily broken, but able to regenerate. Although it is not entirely clear how brittle stars detect light, a recent microscopic view of the brittle star, Ophiocoma wendtii, has led scientists to believe some species may use tiny crystalline lenses covering each arm collectively to see like a giant compound eye.
UCSC Student Intern Jessica Bella wanted to know how brittle stars reacted to different wavelengths of light or intensity. She decided to study a local species of brittle star common to Monterey Bay . The species, Ophiopteris papillosa, is a chocolate brown animal with long, blunt spines lining each of its five arms. You can see this interesting creature and other colorful brittle stars up-close when you visit the Seymour Center this summer!
Jessica employed thirty-six brittle stars total. She measured the distance a brittle star traveled when exposed to red, blue or white light of known wavelength and intensity. Red and blue light were used because they are on opposite ends of the visible light spectrum. White light contains both red and blue wavelengths.
What did Jessica find out? Predictably, the brittle stars reacted more to brightly lit conditions than dim ones. But here’s something new… Ophiopteris papillosa responded more to red light than to either blue or white light. Why? Well, that’s a good question. Isn’t it?
Big skate egg!
Skates are cartilaginous fishes, like sharks and rays. One species, the big skate (Raja binoculata), grows to a whopping eight feet (2.4 m) long and is found swimming along sandy seafloors where it searches for clams, shrimp, worms, and fish to eat.
Bay pipefish (Syngnathus leptorhynchus):
Innkeeper worms (Urechis caupo) are plump, sausage-shaped marine invertebrates that live within the sandy mud of bays and estuaries along the California coast. Innkeepers burrow in the mud creating u-shaped tunnels with each end of the tunnel reaching the seawater above. People who explore California's mud flats at a negative low tide often find the entrances to innkeeper worm burrows exposed by the receding tide water.
An innkeeper worm uses an interesting method to collect food without ever having to leave its muddy home. First, the worm secretes a cylindrical mucus net within its u-shaped burrow. Then, using peristaltic waves of muscle contractions along the length of its body, the worm pumps seawater through its burrow, bringing in small organic particles that stick to the mucus net. Once the mucus net is coated with edible particles the worm simply eats the net with the food.
As its common name implies, the innkeeper worm often shares its home with other animals. The most common animals found in the innkeeper's burrow include pea crabs, scale worms, and fish (family: Gobiidae). The type of symbiotic relationship between the innkeeper worm and its "guests" is commensal - the innkeeper neither benefits, nor is it harmed, by sharing its burrow, but its guests receive shelter and feed on food particles discarded by the innkeeper.
This month, Seymour Center visitors can observe our resident innkeeper worms sharing their burrows with several new pea crabs. The innkeeper worms are housed in custom-made transparent glass "burrows" so they may be easily observed.
Click here to download a 2.6 MB QuickTime movie and see how an innkeeper worm pumps water through it's burrow (courtesy of MetaVisual, Inc.).
Moon jellies: The question posed above the Seymour Center's jelly tank "How can we study it?" was cleverly crafted to allow maximum flexibility for displaying many different species of jellies and other plankton. The exhibit signage above the jelly tank describes how researchers meet the challenges of keeping jellies in aquaria rather than focusing on a single species. With that said, we now have moon jellies (Aurelia aurita) drifting in the jelly tank! The moon jellies are approximately six months old and measure 10 cm (4 in) in diameter. Moon jellies grow to 50 cm (20 in) diameter - at that size they would no longer fit in our jelly tank. Since our building dedication last January we have been able to display several different species gelatenous plankton: sea nettles, sea gooseberries (ctenophore or comb jelly) and now moon jellies!
Brittle Star: A special type of brittle star has been added to the aquarium. The newcomer is a basket star (Gorgonocephalus eucnemis), one of the largest forms of brittle stars known. With its five dichotomously branched arms fully extended the basket star can reach a total diameter of over one-half meter (1.6 ft). The basket star's arms are held above the central body of the star to form a basket-like network of branches that are used to capture drifting plankton. Here at the Seymour Center the basket star is fed nutritionally enriched brine shrimp and tiny pieces of prawn.
This species of basket star prefers cold temperatures so the seawater in the basket star exhibit is cooled down to a chilly 6° C (43° F). The normal temperature of seawater flowing through other exhibit tanks is 12° C (54° F). Here along the central California coast basket stars are typically found in deeper water where the temperature is cooler. This particular basket star was found at a depth of 40 fathoms (240 ft) in Monterey Bay.