Most people never get the chance to encounter a shark and discover how unthreatening many species are. Those who dive or snorkel in Catalina waters may have a chance to observe one of the gentlest sharks around, the horn shark. They are found in Lover's Cove, Descanso Bay, the Dive Park and elsewhere around the island.Most people never get the chance to encounter a shark and discover how unthreatening many species are. Those who dive or snorkel in Catalina waters may have a chance to observe one of the gentlest sharks around, the horn shark. They are found in Lover's Cove, Descanso Bay, the Dive Park and elsewhere around the island.
The horn shark is also found from central California south to the Gulf of California and possibly South America. In our state it is rare north of Pt. Conception. Interestingly its species name (francisi) refers to San Francisco where it must be quite rare if present at all. It is a "lazy" bottom dweller, and rarely swims more than a few feet above the ocean floor. They are most common around rocky reefs and kelp beds although the young can be found on shallow sandy bottoms.
Horn sharks are brown or gray in color with black spots on their bodies. Their head region is farely distinctive with a ridge along each eye. Be careful when you encounter them because these sharks have sharp spines at the forward edge of each dorsal fin. Although harmless, I did experience one horn shark "attack." I was trying to gently relocate a larger one to get better footage. It was not happy with my effort and swam up to my chest, biting my wetsuit several times before swimming off. My response was uncontrolled laughter, causing my try regulator to fall from my mouth, since their teeth are designed for crushing rather than tearing flesh (or even neoprene).
Dr. Milton Love states that in Catalina waters the horn sharks appear to move from deep water (> 120 ft.) to shallow water during the summer. The larger (> 1 ft.) ones return to deeper water as winter approaches. This may be related to reproduction, since egg development would occur faster in the warmer shallow waters. Both genders mature at about two feet in length. Actual mating occurs in the "depths" of winter and the females lay their eggs from February through April. Horn sharks lay interesting eggs with tough cases and spiral processes on them. Some people think the female drops her eggs as she swims, and they spiral to the bottom. Actually the females appear to wedge the eggs into holes and crevices where the spiral flutes help secure them. This species is one of the few in our area that lays eggs instead of giving birth to young which develop inside the female's body. The small (6") juveniles hatch after 7-9 months.
Recently I've been observing several horn sharks ranging in size from 18" to nearly 3 ft. (almost their maximum size) in the Dive Park. I rarely do night dives when they are most active in our waters (too much fun to have topside at night!). During the day I find them resting in the crevices and "caves" of the Casino breakwater. The large one appears to return to the same cave each day. Dr. Love states that horn sharks with short dorsal spines rest in rocky crevices where their spines are subject to some wear due to the continual surge. Those with long spines appear to prefer resting in algae where their spines are not easily worn down.
As might be expected, these fish are nocturnal (night) feeders. The young ones feed on worms and other invertebrates. Older fish prefer fish, squid, crabs, sea urchins and other adult fare (and probably eat at separate tables during the holidays!). It is reported that our own Catalina bald eagles will feed on them, which I find interesting since the eagles are airborn predators whereas the horn shark is active at night and usually close to the bottom. Eagles must be taking them as smaller juveniles in the shallow and intertidal areas.
© 2004 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.
Head of small horn shark in cave; sharp spine at front
of first dorsal fin; small
horn shark swimming in dive park; horn shark egg showing spiral processes
This document maintained by
Dr. Bill Bushing.
Material © 2004 Star Thrower Educational Multimedia