Scientists Discover Vampire Squid's Unique Reproductive Strategy

Scientists have discovered that vampire squid, which live in the deep depths of the ocean, boast a unique reproductive strategy that differs from all other living coleoid cephalopods, according to a new study.

While other squid reproduce all at once late in their lives, vampire squid appear to alternate between reproductive and resting phases - a pattern of multiple spawning more common among fish.

"We know very little about deep-sea organisms and their life-cycle patterns, in particular in the water column of the deep sea," Henk-Jan Hoving, from the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany, said in a press release. "The patterns we know from coastal and shallow-water organisms may not apply to deep-sea species."

Vampire squid got their name, not because they feast on blood, but because of their big red eyes and darkly colored, cloak-like webbing, according to Discovery News. Compared to other squid and related soft-bodied cephalopods, they live life at a much slower pace. At ocean depths from 500 to 3,000 meters (~1,600 to 10,000 feet), they don't swim so much as float, and they get by with little oxygen while consuming a low-calorie diet of zooplankton and detritus.

Hoving and his team were going through the vampire squid collections from the 60s and 70s at the Santa Barbara Museum of Natural History, when they found something they did not expect.

Many of the female vampire squid had spawned, but they had no ripe or developing eggs and were in a reproductive resting phase - a unique strategy considering most other squid reproduce all at once.

The researchers decided to investigate more than 40 female vampire squids. They found that one female in particular, despite being in a reproductive resting phase, had released at least 3,800 eggs yet still retained 6,500 viable oocytes (immature reproductive cells) for future spawning. Assuming an average batch size of 100 eggs, the researchers suggest that this one female had already spawned about 38 times, with eggs in reserve for another 65 or so spawning episodes.

That means vampire squid could have about 100 times more sex than other squid do!

The findings also suggest that vampire squid live longer than shallow-water squid species typically do, showing just how little we know about life in the deep sea.

"We need to enhance our knowledge of deep-sea pelagic organisms and the system they are part [of], since the pelagic deep sea is the largest living space on the planet," concluded Hoving. "A better understanding of this unique marine ecosystem will eventually allow for better development of management and conservation strategies."

The findings were published in the journal Current Biology.

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