DIVE DRY WITH DR. BILL #872: STALKED BY A LEOPARD
COVID-19 has had some interesting impacts on King Neptune's realm. No my fine finned friends have not caught the disease. I'm always very careful to wear a mask when I descend in our waters... a dive mask, of course. Wouldn't be prudent to dive without one even though it isn't an N95.
Back when diving in the park was curtailed, I did a dive out towards the wreck of the Suejac at the far end of the park. As I cruised along at about 40 fsw, I saw a soupfin (aka tope) shark swimming in the same direction about 30 ft below me. Cool, I can't remember seeing one inside the park. Then when the City closed the park, I would walk out there to sit and read my latest book. Several times I was pretty certain I saw a shark's dorsal fin at the surface. With none of those nasty Homo sapiens in the water to harass them, they were free to enter.
Then the dive park opened back up. Despite the summer hordes of snorkelers, we kept seeing sharks that are generally fairly shy. I'm talking about those "vicious" leopard sharks (Triakis semifasciata). Actually these sharks are often a bit skittish when humans are present and would make a dismal episode on Shark "Weak." I have dived with them in many other places off Catalina as well as down in Sandy Eggo.
Years ago my two sisters and I were kayaking back to Avalon when I spotted a school of these timid beasts. In a death defying move, I jumped out of my kayak and swam with these vicious killers (if you're a small fish, a crab, a shrimp, a worm or other prey which they feed on using suction). I called out to my sisters that it was their chance to swim with the sharks, but they refused to join us. I re-entered my kayak with all fingers and toes intact.
Leopards are fairly small sharks, averaging four to five feet in length. Large females may reach six feet. They have a short, rounded snout. The first dorsal fin ius about halfway between the pelvic and anal fins and the second one is almost as large. The tail or caudal fin has an upper lobe about twice as long as the lower lobe. Body color is silvery to gray and is covered with dark "saddles" and spots. The belly is light in color.
This species is found from Oregon to Mazatlan, Mexico. During summer schools of them enter shallow water, most likely because the warmer temperature accelerates development of the young. The pups develop inside the female, taking nourishment from the egg yolk. The gestation period is 10-12 months and a female may give live birth to as many as 37 youngsters between March and June. Good thing they don't have to pay for child care! The ladies are a bit promiscuous and may mate with several males (who, obviously, have the same sexual proclivities).
Several scientific names were given to this species. Of course when addressing one another they go by their own names... Mary, Bob, Annette and Cornelius. In 1851 a British zoologist used the name Triakis californicus, but failed to give a scientific description for it so the name was deemed inappropriate. Two more names were suggested, the first (Mustelus felis) in 1854 and the currently accepted name the following year. There was an error in recording the dates for each of these and the later name became the one we use today. Biologists have specific procedures for naming species.
Although often found in enclosed bays with mud or sand bottoms, they can also be observed around rocky shores with kelp beds. In years past I had only seen two individuals in the dive park, both out by the wreck of the Suejac. Within one week I matched that by seeing two in the shallows (~20 fsw) near the dive park stairs. In fact, I was adjusting the neck strap on my BCD when the second one almost ran into me at a distance of a few feet!
© 2020 Dr. Bill Bushing. For the entire archived set of over 850 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Leopard sharks in shallow water.
COVID-19 has had some interesting impacts on King Neptune's realm. No my fine finned friends have not caught the disease. I'm always very careful to wear a mask when I descend in our waters... a dive mask, of course. Wouldn't be prudent to dive without one even though it isn't an N95.
Back when diving in the park was curtailed, I did a dive out towards the wreck of the Suejac at the far end of the park. As I cruised along at about 40 fsw, I saw a soupfin (aka tope) shark swimming in the same direction about 30 ft below me. Cool, I can't remember seeing one inside the park. Then when the City closed the park, I would walk out there to sit and read my latest book. Several times I was pretty certain I saw a shark's dorsal fin at the surface. With none of those nasty Homo sapiens in the water to harass them, they were free to enter.
Then the dive park opened back up. Despite the summer hordes of snorkelers, we kept seeing sharks that are generally fairly shy. I'm talking about those "vicious" leopard sharks (Triakis semifasciata). Actually these sharks are often a bit skittish when humans are present and would make a dismal episode on Shark "Weak." I have dived with them in many other places off Catalina as well as down in Sandy Eggo.
Years ago my two sisters and I were kayaking back to Avalon when I spotted a school of these timid beasts. In a death defying move, I jumped out of my kayak and swam with these vicious killers (if you're a small fish, a crab, a shrimp, a worm or other prey which they feed on using suction). I called out to my sisters that it was their chance to swim with the sharks, but they refused to join us. I re-entered my kayak with all fingers and toes intact.
Leopards are fairly small sharks, averaging four to five feet in length. Large females may reach six feet. They have a short, rounded snout. The first dorsal fin ius about halfway between the pelvic and anal fins and the second one is almost as large. The tail or caudal fin has an upper lobe about twice as long as the lower lobe. Body color is silvery to gray and is covered with dark "saddles" and spots. The belly is light in color.
This species is found from Oregon to Mazatlan, Mexico. During summer schools of them enter shallow water, most likely because the warmer temperature accelerates development of the young. The pups develop inside the female, taking nourishment from the egg yolk. The gestation period is 10-12 months and a female may give live birth to as many as 37 youngsters between March and June. Good thing they don't have to pay for child care! The ladies are a bit promiscuous and may mate with several males (who, obviously, have the same sexual proclivities).
Several scientific names were given to this species. Of course when addressing one another they go by their own names... Mary, Bob, Annette and Cornelius. In 1851 a British zoologist used the name Triakis californicus, but failed to give a scientific description for it so the name was deemed inappropriate. Two more names were suggested, the first (Mustelus felis) in 1854 and the currently accepted name the following year. There was an error in recording the dates for each of these and the later name became the one we use today. Biologists have specific procedures for naming species.
Although often found in enclosed bays with mud or sand bottoms, they can also be observed around rocky shores with kelp beds. In years past I had only seen two individuals in the dive park, both out by the wreck of the Suejac. Within one week I matched that by seeing two in the shallows (~20 fsw) near the dive park stairs. In fact, I was adjusting the neck strap on my BCD when the second one almost ran into me at a distance of a few feet!
© 2020 Dr. Bill Bushing. For the entire archived set of over 850 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Leopard sharks in shallow water.
