Posted on July 20th, 2015
It is always good to be reminded why I like being a professor, and this was one of those days. Every summer we have lead a CMBC cruise to the offshore waters of San Diego. This year we made two amazing net hauls next to the Coronado Bank. The first was from ~200 m and was full of some 170,000 tuna crabs–the harbingers of el Nino–who have been mass stranding on the beaches of late. Well, now we know where they come from! I felt like I was on a trawler from the days-of-yore before industrial fishing. This haul also had a neat octopus, urchins, fish and spider crabs.
Then came the mid water tow at 550 m, and it was loaded with wonders too–the kind that Hollywood film makers should love and are the stuff of nightmares as you toss and turn in the dawn hours. We caught three kinds of Dragonfish, two species of Hatchet Fish, an angler, a Snipe eel with a whiplike tail, and the most wild of all–a Loose Jaw, that looks like it was mangled, but really has almost nothing holding its jaw in place! These fish reside in a world that is physically not that far from ours (it probably takes 5 minutes to walk 500 m!) but is almost totally different anyway! Majesty! Wonder! Thrills! And Fascination!
What gets me is how alien their world is. These are fish attract their prey with lighted lures, sense their prey by pressure, and make sure they don’t lose their prey by attacking with huge nasty teeth. The hatchet fish have eyes that permanently look upward to spot the faint shadow of prey above them. And most everybody has rows of photophores on their bellies to keep from casting a shadow on some larger fish below them. The photophores are like miniature flood lights, complete with a black case and a crystalline lens. The world is full of things more bizarre and exciting than most people know. Beat’s landing on the moon any day…It really was one of the great adventures in my life….
Best is to have a crowd of students to share the adventure.
A Loose Jaw (Malacosteus) from the mid water off San Diego. Note the red and silver light organs under the eye. The fish has a jaw that can be swung forward to engulf prey bigger than it….Check out the hooks on the teeth–I’ve seen those before in the fossil record!
Greg Rouse on the hunt for monoplacophorans. We got lots of neat sponges, starfish, limpets and bryozoans, but no monoplacs for the 5th year running….
Another strategy in the deep is to be transparent… Evolution somehow managed to make the compound eyes of these amphipods almost completely transparent. The eyes, by the way are the whole front end (!!)…vision must be pretty important even at 550 m in the ocean….But what can you see if your photo-sensing pigment is transparent?
Tuna crabs sure are cute….They swim by pumping their tails backwards trailing their long claws behind them…..
The crab-pile, along with a few urchins and fish…There is still is a bounty in the sea… We put this bounty back in the ocean and I was amazed to see that quite a few, perhaps the majority, swam away kicking their tails…back to the ocean depths. But we did observe a blue whale lurking nearby, so perhaps this is whale food….
Kate Masury (MAS-MBC-2015) with some of our load of tuna crabs…
Too many tuna crabs–a Otter-trawl load with more crabs than I have ever seen. Greg Rouse estimated 170,000. We shoveled them back into the sea and I imagine a fair number survived since they were wriggling all over the deck. But both amazing and a bit distressing to catch so many. The trawl filled up almost immediately upon reaching the bottom. We either went through a swarm of them, or there are a Sh*t-load of crabs out there at 200 m! Phil Zeroski for scale….
The world really is stranger than we can know…This thing is a ‘Snipe eel” (Nemichthys)–a true eel that has this amazing jaw whose upper mandible curves upwards away from the lower jaw! The jaws are lined with dinky teeth that point backward into the gullet–a veritable Chinese finger trap in the fish world. Even more remarkable is the tail…. About half the body length is a tail about the thickness of thread, but the vertebrae apparently run to the end. What is that ‘whip’ used for? A lure? Pressure sensing? Feeling the prey before a strike? “Feeling” up its sweetie before some other kind of behavior?
Hatchet fish from the mid water in the Coronado Trough off San Diego. Its eyes look up to search the overlying water for the shadows of prey and its belly is lined with light organs to avoid casting a shadow that could make the fish somebody else’s lunch! It would pay to be a vampire in the deep!
This octopus was delighted, no doubt to be released back to the sea after making a home in my glass basin…
Dragonfish type 2 (the Viperfish, Chauliodus). These guys have more massive teeth than the other two species. …Perhaps they go for really big game…The lure under the jaw is actually a modified dorsal fin! …deeply amazing, if you ask me!