Beachcombers commonly find washed up jellyfish along Kachemak Bay. Did you know that among those stranded jellies may be one of the most scientifically important bioluminescent marine organisms in the world?
The water jelly (Aequorea victoria) is a graceful and nearly transparent invertebrate with long, delicate tentacles. This bioluminescent jellyfish, ranging from the Bering Sea to southern California, is abundant in Kachemak Bay.
The water jelly, also know as the many-ribbed hydromedusa or crystal jelly, contains the luminescent protein aequorin and the fluorescent molecule GFP (green fluorescent protein).
In 1961, these proteins were isolated, extracted, purified and cloned. Since then, scientists have inserted the GFP gene from the water jelly into mice, creating "green mice" that glow green under blue light.
This glowing protein is a widely used biological "highlighter" that helps scientists find and study genes more quickly.
Both proteins are currently being used to pursue exciting new capabilities, such as tracking bacterial infection and detecting chemical and biological agents planted by terrorists. In addition, glowing genes created with these proteins are employed to kill and image cancer cells and light up the presence of some types of pollution.
Water jellies are almost impossible to see and emit light only around the margin of the animal's bell. In optimal viewing conditions, the bioluminescence would resemble a string of extremely small, green lights. It is unknown what purpose this cold light serves or how it may benefit these jellyfish.
Adult water jellies only grow to an average of about 5 to 10 centimeters (2 to 4 inches) in diameter; however, in Alaska this species commonly reaches as much as 20 centimeters (7.9 inches).
They feed on soft-bodied prey, including other, smaller jellyfishes, and probably live six months or less, with the entire population dying off by mid-autumn every year. Polyp colonies persist on the bottom of the ocean and produce a new generation of medusae each spring. The factors that trigger this asexual budding in the spring are still unknown.
These beautiful jellies are often found near the surface of Kachemak Bay during summer months. If you pick up a stranded water jelly at night and shake it gently in your hand in the dark, you will see the ring of green bioluminescence along the bell's margin (you cannot feel their sting but be sure you know which species you have).
The light lingers only a few seconds, and some luminescent particles may stick to your hand after you put the animal back on the beach or in the water.
If you have questions about Kachemak Bay, contact the Research Reserve staff at 235-4799 or visit the Web site at www.kbayrr.org.
Ingrid Harrald is an education associate at the Kachemak Bay Research Reserve.
