Thursday, February 26, 2009
This handsome fella/femme is a reef stonefish, most likely Synanceia verrucosa. Most people have heard of stonefish, as they are some of the most venomous fishes in the world, but few get to appreciate their beauty up close. Not surprisingly (considering Australia's track record), they tend to hang out in the indo-pacific region, especially on Australian reefs. They possess thirteen stiff spines on the front part of their dorsal fins, from which the venom can be injected.
They don't use their venom to hunt, but only for protection from predators (and humans). For hunting, they prefer to sit motionless on the reef and snap at passing shrimp and fish. They are beautifully adapted to blend in with the reef and reef rubble, right down to the bright orange blotches that mimic the color and shape of the sponges that grow on the rubble. Fantastic!
Thursday, February 12, 2009
This fish is the plainfin midshipman (Porichthys notatus). If you were looking at the top of the fish, you would see a plain grayish fish with a rather large mouth. One of the midshipman's interesting features actually lie underneath the fish. These interesting dots on the underside of the fish are photophores, which can produce a bright light pattern. Its still not clear what the light is for, but some speculate that the midshipman uses them to lure prey closer when hunting. The midshipman will hang in the water column and flash its light to attract prey items.
Interesting thing number 2 is how midshipman reproduce. Like most fish, males are responsible for maintaining the nest and attracting the females to lay their eggs. Male midshipman will hum for hours on end to attract females to their nest. The hum is produced by the fish vibrating their swim bladder, and can be so loud that people walking on a beach can hear it (and people living on boats often find it hard to sleep). Female midshipman who are producing eggs (more estrogen) are more sensitive to the humming noise and more likely to seek out its source .
Here's a nice news article on the midshipman's love life, with some sound bytes attached (for Quicktime viewers only).
Sunday, February 8, 2009
Seven gill sharks are called that because unlike most modern day sharks, which have five gill slits on either side of their head, seven gills have seven. There are only a few other sharks which have more than five gill slits, namely the six gill shark, and the sharp-nose seven gill shark. These sharks are considered some of the most primitive sharks alive today. The seven gill generally hangs out under the golden gate bridge area, as it is the deepest part of San Francisco bay. They are also the largest shark in the bay, reaching 10 ft (~ 3 m) in length. The largest shark in the area, the white shark, does not enter the bay as it cannot tolerate the brackish water.
Back in the day, these guys were heavily fished for their oily liver. The fishery in San Francisco collapsed in the 1940s due to heavy fishing. They seem to be making a bit of a comeback, although there is no official data on their status. They are doing a tagging and tracking study on these guys, to see exactly how they use the bay, so maybe we can also get a better idea of population numbers too.
Thursday, February 5, 2009
This lovely fellow is the flapjack octopus or Opisthoteuthis californiana. Normally deep water creatures, this guy was caught ~1,000 ft (~333 m) from the surface off the coast of California. He possesses very large eyes, which help him find food using the barest glimmer of light that reaches those depths. There really is not much known about their diet, lifestyle, or even distribution (although they've caught them off of California and Japan).
They think that these guys are benthic, but they do have two very distinct swimming modes. The first is pretty common to all octopuses and squids; jet propulsion. They can squirt out a stream of water from their mantle which pushes them head first through the water. The second swimming mode is less common among octopuses. They can use the flaps attached to their heads as fins to swim.
Enjoy this video our flapjack friend swimming about...