Docile to us and predators to invertebrates, the leopard shark (Triakis semifasciata) are relatively small and timid sharks. Divers are lucky to glimpse these sharks, as they tend to steer clear of us. A few albino leopard sharks have actually been spotted and photographed before! Growing up to a maximum of 1.8 meters (nearly 6 feet) in their 30 year lifespan, they can have anywhere from 4-33 pups every 12 months. It takes 10 years after birth for them to sexually mature!

They’ll grow up living anywhere in the eastern Pacific Ocean. Often, they stay near the bottom of shallow, sandy/muddy bays because food is abundant there. Being active, strong swimmers, they are able to school and move around frequently. What’s awesome about that is other sharks have joined in, including but not limited to: brown smooth-hounds, gray smooth-hounds, and piked dogfish. 

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Leopard Sharks, Triakis semifasciata

Leopard sharks, Triakis semifasciata (Girard, 1855), are members of the Houndsharks Family, TriakidaeZebra sharks,Stegostoma fasciatum, are commonly confused with leopard sharks and share the same common name in Australia and SE Asia. Leopard sharks have short, broadly-rounded snouts, their first dorsal fins are moderately large and its origin is over their pectoral fins’ inner margins. Their second dorsal fin is nearly as large as the first one (height is about 3/4 of the first dorsal fin) and their anal fins are much smaller than their second dorsal fins. Their pectoral fins are broadly triangular and they have very conspicuous dark saddles and dots on their bodies. They have gray to bronze-gray upper bodies with light ventral (under) surfaces. Their average size is between 1.2-1.5 m and their maximum total length is about 1.8 m. Leopard sharks can weigh up to 18.4 kg and live as long as 30 years.

World Range & Habitat

Leopard sharks are found in the Eastern Pacific Ocean: from Oregon to the Gulf of California, Mexico. They are currently an abundant species in cool and warm-temperate waters. They are found inshore and offshore in continentallittoral waters. Most common on or near the bottom in shallow waters, between 4-90 m. They prefer sandy or muddy bays. They are active, strong swimmers and are known to form large schools that seem to be nomadic. The swimming motion of this species is described as undulating. Leopard sharks are often seen together with brown smooth-hounds,Mustelus henlei, and gray smooth-hounds, Mustelus californicus, or the piked dogfishSqualus acanthias.

Feeding Behavior (Ecology)

Leopard sharks, Triakis semifasciata, feed primarily on bottom-living invertebrates. Other small sharks have also been found in their stomachs. Their diet seems to change with seasons and their age/size.

Life History

Leopard sharks are aplacental viviparous (ovoviviparous) and they produce between 4-33 pups per litter after a gestation period of about 10-12 months. Their size at birth is about 20 cm, usually in April-May, and they grow very slowly. They reach maturity at an age of about 10 years, males at a size between 0.7-1.2 m, females at approximately 1.1-1.3 m, respectively.

Ovoviviparous: eggs are retained within the body of the female in a brood chamber where the embryo develops, receiving nourishment from a yolk sac. This is the method of reproduction for the “live-bearing” fishes where pups hatch from egg capsules inside the mother’s uterus and are born soon afterward. Also known as aplacental viviparous.

Conservation Status & Comments

Leopard sharks are harmless to humans. This mid-sized coastal shark is fairly common in bays and estuaries and are taken both commercially and by recreational anglers.

Although a slow-growing, late-maturing shark with low productivity, management introduced in recent decades has reportedly protected the core of the population in California and Oregon waters from overfishing. Little is known of the stock status in Mexico.

Leopard sharks, Triakis semifasciata, are listed as Least Concern on the IUCN Red List of Threatened Species

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Leopard Shark, Triakis semifasciata.

One of the most popular animals at MSI is the leopard shark. We keep 8 or 9 baby leopard sharks in our aquarium at a time. We catch the sharks when we take our 90 foot research vessel out on the San Francisco Bay. The leopard shark is a beautiful animal covered with dark saddles and splotches. The top of the animal varies in color from silver to a bronzed gray. Leopard sharks are most commonly found in shallow bays and estuaries but sometimes live in the kelp forest, usually staying near the bottom.

Leopard sharks love to eat benthic invertebrates like mussels, clams, crabs, and worms. Male leopard sharks can grow to be 5 to 6 feet long while the females can grow to be 6 to 7 feet long!  These sharks are very gentle creatures and both kids and adults love getting the chance to touch the sharks when they come to visit MSI!

A Polyhedral Journey, Beginning with a Near-Miss Johnson Solid Featuring Enneagons

When Norman Johnson first found, and named, all the Johnson solids in the latter 1960s, he came across a number of “near-misses” — polyhedra which are almost Johnson solids. If you aren’t familiar with the Johnson solids, you can find a definition of them here. The “near-miss” which is most well-known features regular enneagons (nine-sided polygons):

This is the dual of the above polyhedron:

As…

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A short aerial film showing the beauty of Cape Town and its surrounding area, including Lion’s Head, Table Mountain, Cape Point, Hout Bay, Simon’s Town, and Seal Island. Footage includes great white sharks from above at Seal Island, an aggregation of spotted gully sharks / sharptooth houndshark (Triakis megalopterus) in the surf near Cape Point in Table Mountain National Park, and a sea lion surfing in the waves.

I shot this footage back in August, but only did the edit today; if you are interested in what I was doing with aerial imaging in South Africa, you can see all of the posts from that timeframe here.

Shot with DJI Phantom 2 / Zenmuse H3-3D gimbal / GoPro HERO 3+ Black. All footage was captured in ProTune at 2.7/30p or 1080/60p and run through GoPro Studio for GoPro Color conversion and perspective correction, and then edited in Adobe Premiere Pro CC 2014 with minor grading in Magic Bullet Looks.

Amazing footage of Cape Town from a drone

Eric Cheng is film maker that specialises in footage shot from a drone He has shot some incredible footage from around the world. He posted the clip of Cape Town last week.

A short aerial film showing the beauty of Cape Town and its surrounding area, including Lion’s Head, Table Mountain, Cape Point, Hout Bay, Simon’s Town, and Seal Island. Footage includes great white sharks from above at Seal Island, an aggregation of spotted gully sharks / sharptooth houndshark (Triakis megalopterus) in the surf near Cape Point in Table Mountain National Park, and a brown fur seal surfing in the waves.

http://bit.ly/1zkNI9s

vimeo

Aerial Cape Town, South Africa, by Phantom 2 from Eric Cheng on Vimeo.

A short aerial film showing the beauty of Cape Town and its surrounding area, including Lion’s Head, Table Mountain, Cape Point, Hout Bay, Simon’s Town, and Seal Island. Footage includes great white sharks from above at Seal Island, an aggregation of spotted gully sharks / sharptooth houndshark (Triakis megalopterus) in the surf near Cape Point in Table Mountain National Park, and a brown fur seal surfing in the waves.

Shot with DJI Phantom 2 / Zenmuse H3-3D gimbal / GoPro HERO 3+ Black.

Shortcuts:
00:03 Lion’s Head
00:34 Lion’s Head dronie
00:44 Table Mountain
00:57 Cape Point kelp
01:20 Cape Point shark aggregation
01:36 Fur seal scares sharks
01:45 Fur seal surfs
01:51 Buiker Island
02:11 BOSS400 crane barge
02:21 Animal Oceans dronie
02:33 Seal Island
02:55 Great white sharks
03:27 Simon’s Town approach
03:46 Credits

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