June 4, 2017

John Pogonoski with a lizard fish
Something you don't want to meet in the deep. John Pogonoski of the CSIRO Australian National Fish Collection with a lizard fish caught on the CSIRO RV Investigator voyage to sample the abyss. Image: Asher Flatt

Blogging the abyss iconDay 21: Asher Flatt, onboard communicator

There are still monsters in the deep dark places of the world, at least there are if you're an unsuspecting deep-sea fish. One of the many things lying in wait to eat you is the deep-sea lizard fish (Bathysaurus ferox).

This terrifying terror of the deep is largely made up of a mouth and hinged teeth, so once it has you in its jaws there is no escape: the more you struggle the further into its mouth you go.

Being the dominant predator of the depths isn't easy though: at depths of 1000–2500 metres there is very little food, so lizard fish are few are far between to maximise scarce resources.

And love can be even harder to find in the deep than a meal, a struggle that has nudged the lizard fish down the evolutionary path of a hermaphrodite. They have both male and female reproductive organs, so whatever other Bathysaurus ferox they come across will be Mr right and Miss right. How could you not love a face like that!

John Pogonoski of the CSIRO Australian National Fish Collection recognised this fearsome predator as soon as he removed it from the beam trawl on the RV Investigator.

“I noticed the long dorsal fin base characteristic of Bathysaurus ferox (the only other species in the genus, Bathysaurus mollis, has a short dorsal fin base and a very small second dorsal fin near the tail)," John says. "The large eyes and teeth are classical features of an ambush predator.” 

Baby Lizard Fish
Even the babies are all eyes and teeth. Image: Asher Flatt
John Pogonoski with a lizard fish
All the better to eat you with! Image: Asher Flatt
Voyage date: 
Sunday, June 4, 2017


Love the humour! What a great blog post about an interesting animal!

Why is there an opening in the middle of its bottom jaw?

The opening you refer to is simply the ventral opening of the gills. The large gill openings help the fish pump water through their gills when in a stationary position and probably also help the fish expand its mouth wide open when they ambush and seize their prey (food) items.

Great to see my old friend from another lifetime. I can remember catching ferox on the R/V Eastward in the 1970's and preserving a sample of the gonadal tissue while processing the catch. The sample showed it was hermaphroditic; others showed the tripod fishes and other benthic fishes of their ilk were also hermaphrodites. The article brought back many fond memories of standing on the fantail waiting for the tail-bag of a benthic trawl to be tripped open and catch dumped. It took forever set and haul the trawl in 3000 meters of water. Hope you have as much fun as I had. Charlie

I think the excitement of the trawl coming up is intensified by the long wait from the murky depths. We were retaining the few representatives of each species collected for taxonomic collections, so the more traditional biological sampling (e.g. gut contents and gonad examination) was not done on our voyage. It is interesting to hear about your biological findings on the family Ipnopidae. Hermaphroditism is now a well-established concept for these fishes, but biological data had to be collected from all the species to get to that point.
John Pogonoski https://people.csiro.au/P/J/John-Pogonoski