I am writing this just having complete the process of the catch of the last dive of the cruise. That was a very busy day. We had two dives, almost one immediately after the other, exploring the cliffs, slopes and flat areas and collecting specimens. As usual we collected the most common animals that will help us to identify them on the video transects. One of our achievements is that we collected a fully intact specimen of an enteropneust (acorn worm), the first whole specimen that has been ever collected and preserved, thanks to Dave Edge!
Many benthic and benthopelagic animals leave trails of their activity on the seafloor which often described by the german word «lebensspurren». Studying these trails is resembles a job a pathfinder. These trails can say many interesting things about life in the deep sea: what animals are living here, what are they doing and how they are feeding. For burrowing animals lebenspurren are the only evidence of their presence in the studied area.
Some lebensspurren are well known and recognizable. Echinoids leave long narrow trails by their long spines and feeding on organic matter in the sediment:
Holothurians leave their faeces:
Some fish also leave trails while staying on the seabed:
Echiurid or spoon worms are burrowing worms that put out of burrow their long proboscis looking for food. Their proboscis can stretch to one metre in length leaving amazing star –shaped trails on the seabed.
The spiral trail of an acorn worm.
But sometime we observed something mysterious.
These trails are very similar to «fairy rings» – enigmatic trails on the Porcupine Abyssal Plain in the North-East Atlantic. It represents a hill sometime almost a 1 m in diameter surrounding by large holes. After tens years of their observation it is still unknown what animal could make it.
On the South-East site we also find some enigmatic trails.
These trails could reach a few metres in length and resemble giant stitches.
There are many intriguing things at the deep sea that are waiting for being discovered and explained.