DIVE DRY WITH DR. BILL #756: ORBICULAR CARDINALFISH
This Christmas I received several very nice gifts. Santa was good to me even though I'm not always a "good" boy! One of them was a copy of Marine Environments of Palau sent to me by Chris Lubba, co-owner of Palau Dive Adventures. I dove with them exclusively while I was in Palau several years ago and have given talks about Palau for them on occasion. Leafing through this beautiful tome reminded me of my experiences there and my desire to return if my cancer allows me to.
One of the many famous dive sites in Palau is Jellyfish Lake. I was able to snorkle it (no SCUBA allowed) several times, mostly to film the unusual golden jellyfish (Mastigias papua etpisoni) found there. Fortunately this was prior to an El Niño related drought event which caused many of these sea jellies to die off. The jellies were both numerous and exciting to film (fortunately their sting is too mild to feel). But I was also interested in the other critters that live in this unusual environment.
From the moment I jumped off the floating platform into the water, I noted an interesting fish. It was the orbiculate cardinalfish (Sphaeramia orbicularis), also called the chubby or polka dot cardinalfish. These fish are not restricted to the marine lakes of Palau, and are also found in coastal waters throughout the Indo-Pacific including East Africa, Australia, SE Asia, Kirbati, the Japanese Ryukyu islands, Melanesia and Micronesia. They may be seen on coral reefs, mangroves and man-made structures. They prefer shallow waters less than about 20 ft.
This species grows to a maximum size of four inches. It has a grayish body with a thin, dark stripe about midbody and scattered dark spots from it to the tail. These fish are generally nocturnal feeders chowing down on planktonic crustaceans. They usually are found in small schools although I'm not sure what grade level they are in.
According to fishbase.org, the orbicular cardinalfish is sexually mature at 6 cm (2.4") for females and 7 cm (2.8") for males. Courtship and spawning occur shortly before full and new moon. The fish pair off and do their thing. Apparently threesomes are not allowed! The males are mouthbrooders, incubating up to 12,000 eggs in their mouths until they hatch after about 8 days. The larvae are pelagic, swimming about in open water until they settle out.
These tropical fish are said to be common in the aquarium trade but our waters are a little too chilly for them. They belong to the cardinalfish family, Apogonidae. We do have several relatives including the Guadalupe and pink cardinalfish in Catalina waters. They have entered our waters from Mexico during El Niño and other warm water events. Apparently no green card is required.
© 2018 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Famed residents of Jellyfish Lake, the golden jelly, and orbicular cardinalfish including potential courtship interaction.
This Christmas I received several very nice gifts. Santa was good to me even though I'm not always a "good" boy! One of them was a copy of Marine Environments of Palau sent to me by Chris Lubba, co-owner of Palau Dive Adventures. I dove with them exclusively while I was in Palau several years ago and have given talks about Palau for them on occasion. Leafing through this beautiful tome reminded me of my experiences there and my desire to return if my cancer allows me to.
One of the many famous dive sites in Palau is Jellyfish Lake. I was able to snorkle it (no SCUBA allowed) several times, mostly to film the unusual golden jellyfish (Mastigias papua etpisoni) found there. Fortunately this was prior to an El Niño related drought event which caused many of these sea jellies to die off. The jellies were both numerous and exciting to film (fortunately their sting is too mild to feel). But I was also interested in the other critters that live in this unusual environment.
From the moment I jumped off the floating platform into the water, I noted an interesting fish. It was the orbiculate cardinalfish (Sphaeramia orbicularis), also called the chubby or polka dot cardinalfish. These fish are not restricted to the marine lakes of Palau, and are also found in coastal waters throughout the Indo-Pacific including East Africa, Australia, SE Asia, Kirbati, the Japanese Ryukyu islands, Melanesia and Micronesia. They may be seen on coral reefs, mangroves and man-made structures. They prefer shallow waters less than about 20 ft.
This species grows to a maximum size of four inches. It has a grayish body with a thin, dark stripe about midbody and scattered dark spots from it to the tail. These fish are generally nocturnal feeders chowing down on planktonic crustaceans. They usually are found in small schools although I'm not sure what grade level they are in.
According to fishbase.org, the orbicular cardinalfish is sexually mature at 6 cm (2.4") for females and 7 cm (2.8") for males. Courtship and spawning occur shortly before full and new moon. The fish pair off and do their thing. Apparently threesomes are not allowed! The males are mouthbrooders, incubating up to 12,000 eggs in their mouths until they hatch after about 8 days. The larvae are pelagic, swimming about in open water until they settle out.
These tropical fish are said to be common in the aquarium trade but our waters are a little too chilly for them. They belong to the cardinalfish family, Apogonidae. We do have several relatives including the Guadalupe and pink cardinalfish in Catalina waters. They have entered our waters from Mexico during El Niño and other warm water events. Apparently no green card is required.
© 2018 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Famed residents of Jellyfish Lake, the golden jelly, and orbicular cardinalfish including potential courtship interaction.
