When whales die in the open ocean they sometimes sink to the sandy floor where scavenging fish and other marine creatures tuck into the colossal feast. Octopuses, deep-sea fish, crabs and bone-eating worms all turn up for dinner. But there’s one species in particular that gets über-excited when a whale carcass hits the ocean floor: marine researchers.

A team from Monterey Bay National Marine Sanctuary aboard research vessel Nautilus were exploring the ocean depths off the coast of central California recently when they happened upon a baleen whale carcass. The whale remains –estimated to be about 4-5 metres in length – were buzzing with all manner of marine scavengers. The excitement from the team was palpable.

“Oh, here we go, baby!” exclaims one of the researchers as the whale carcass slowly comes into view. The footage was captured by an underwater remote operated vehicle (ROV) called Hercules as part of an expedition that aimed to explore a deep-water region of basaltic rocky reef southeast of Davidson Seamount known as “octopus garden”. The area certainly seems to live up to its name. The carcass was teeming with deep-sea cephalopods scavenging a meal (one researcher can be overheard doing a rough count and concluding that there were at least 15 within view).

“We are so excited up here,” another researcher expresses. And who can blame the giddy scientists? “Whale falls” are rarely seen or recorded and they offer a profoundly candid glimpse into life (and mealtime) in the deep sea. The presence of blubber and some internal organs suggest that the carcass was still relatively fresh, however, there wasn’t enough meat on the bones to allow researchers to positively identify the species.

The whale’s baleen plates – those comb-like structures near it’s head – help to narrow down the options a bit. There are just over a dozen species of baleen whale roaming the earth’s oceans, including blue, humpback and grey. They use their bristly jaw plates to filter the water for prey which can include krill, plankton and small fish. It’s possible that the carcass is that of a juvenile or simply a smaller species of baleen whale. Humpback, minke, blue and grey whales are all found off the coast of California.

Part 2 of the whale fall sighting.

Feasting on the plentiful bounty are an array of organisms. Larger scavengers like eelpouts are seen stripping the skeleton of blubber while bone-eating Osedax worms had taken up residence on the whale’s ribs and vertebrae. Crabs, grenadier, octopuses and bristle worms called polychaetes were all present.

“All their attention is on digestion right now,” one researcher jokes while likening the scavengers to humans vegging on the sofa after a sizeable, celebratory meal.

Whale falls can sustain a variety of life for several years. As a whale’s body decomposes, it enriches the nearby sediment – which becomes a micro-ecosystem of its own. Everything from crabs to sharks and bone-munching worms arrive to feast and reside near the carcass. Once the meat and organs have been stripped away, the skeleton continues to provide a home for bacteria which begin breaking down lipids trapped inside the bones. This generates sulphur which attracts more bacteria and a community of mussels, worms, snails and other species.

Here’s a closer look at the process: