Cephalopods are so unique and incredible – their specialized morphology, their weird and amazing adaptations, their high brain-to-body mass ratio, and their long-stretching evolutionary history – that I've decided to create a weekly feature dedicated to the species of class Cephalopoda. Each week, I will write a post about a cephalopod species and what makes it so awesome. The first two posts will cover the Humboldt Squid (Dosidicus gigas) and the Vampire Squid (Vampiroteuthis infernalis) respectively.
Look out, Jaws
The Humboldt Squid
(Dosidicus gigas)
The Humboldt Squid goes by many names. Mexican fishermen call it the diablo rojo (red devil), based on accounts of Humboldts that flash bright red when attacking their prey. They're also called Jumbo Flying Squid, because like other members of the family Ommastrephidae, they are volplaning organisms – they can eject themselves from the water and use their fins to glide at a height of up to 6 meters above the surface of the water. Their traditional common name comes from the Humboldt Current, a cold, low-salinity, nutrient-rich upwelling system off South America's western coasts, where 18-20% of the world's fish catch comes from and where Humboldts are known to live.
(Dosidicus gigas)
The Humboldt Squid goes by many names. Mexican fishermen call it the diablo rojo (red devil), based on accounts of Humboldts that flash bright red when attacking their prey. They're also called Jumbo Flying Squid, because like other members of the family Ommastrephidae, they are volplaning organisms – they can eject themselves from the water and use their fins to glide at a height of up to 6 meters above the surface of the water. Their traditional common name comes from the Humboldt Current, a cold, low-salinity, nutrient-rich upwelling system off South America's western coasts, where 18-20% of the world's fish catch comes from and where Humboldts are known to live.
A toothy grin
Squid and octopuses are generally known to marine biologists as docile, often solitary animals; they're curious, playful, and easily spooked. The Humboldt Squid (literally) blows that whole notion out of the water. Equipped with 100-200 suckers lined with razor-sharp chitinous teeth (extensions of the calcareous sucker ring), these squid are aggressive and seemingly always ready to attack. They will feed on fishes, smaller squid, and a wide variety of crustaceans. In a pinch, they're known to resort to cannibalism. And why stop there? Here's a video of a young Humboldt attacking a remotely-operated undersea observation device (Humboldts often destroy deep-sea cameras and machinery):
Although Humboldt Squid spend most of their time at depths of 600+ ft., they are occasionally known to have encounters with divers or fishermen – encounters that usually result in painful laceration or injury for the human involved. The squid's baseball-sized beak is capable of ripping hunks of flesh from their prey, although researchers have concluded that Humboldt beaks "lack the strength to crush heavy bones" (big whoop). Humboldts have subcutaneous bioluminescent organs (photophores) on the ventral side of their mantle, head, and arms that they use for communication, counterillumination, and illuminating their surroundings. Fishermen that catch Humboldts use lights to simulate the bioluminescence of the Humboldt's prey, drawing the squids in. Peru is a hot spot for Humboldt fishing; they exported ~400 thousand tonnes of Humboldt meat between the years 2005 and 2007.
Humboldt Squid are highly social animals with a complex system of communication, and while this in itself is not uncommon among squids, they are one of the few cephalopod species of their size to engage in coordinated hunting. Packs of up to 40 Humboldts swim in upward spiral formations, trapping and killing the fish in their path.
Humboldts are sexually dimorphic; the female is larger than the male, a relative rarity in the animal kingdom. Although no courtship ritual has been observed, based on their intelligence and social complexity and observing behaviors in similar species, it's likely some form of courtship occurs. At maturity, one of the males' ventral arms develops into a spermatophore-carrying hectocotylus that fertilizes a mass of 2 million eggs. The parents do not invest in the offspring after fertilization, dying soon after. Humboldts grow to a length of 6-7 ft. and a weight of around 100 lbs. (they are the 4-5th-largest squid species by mass). They mature quickly and only live 1-2 years. Like all squids, they never develop any bone structure, relying on the fluid within their body cavities to support their shape (a hydrostatic skeleton), as well as their 1-metre chitinous gladius (pen).
Humboldts participate in diel vertical migration (DVL), swimming to shallower waters at night to hunt and returning to deep water at dawn. There is more potential prey available in the euphotic zone, and spending the nights in warmer shallower waters allows the Humboldt and other DVL organisms to conserve energy and heat. DVL is central to the biogeochemical process known as the oceanic carbon pump, the ongoing entrance of carbon into seawater as soluble HCO3 ions, its fixation by photosynthetic organisms and its transport to the ocean floor in the form of biomass or as carbon compounds like CaCO3. Most of this transport occurs as detritus (or "marine snow") sinking down into deep waters, but DVL organisms speed up the process by feeding on euphotic life and actively moving biomass-trapped carbon down to the deep, releasing in their waste or remains. The carbon pump is a major part of the global carbon cycle and essential to regulating atmospheric greenhouse gases; it is estimated that one-third of anthropogenic carbon emission are taken up by the ocean through the carbon pump.
Humboldts are sexually dimorphic; the female is larger than the male, a relative rarity in the animal kingdom. Although no courtship ritual has been observed, based on their intelligence and social complexity and observing behaviors in similar species, it's likely some form of courtship occurs. At maturity, one of the males' ventral arms develops into a spermatophore-carrying hectocotylus that fertilizes a mass of 2 million eggs. The parents do not invest in the offspring after fertilization, dying soon after. Humboldts grow to a length of 6-7 ft. and a weight of around 100 lbs. (they are the 4-5th-largest squid species by mass). They mature quickly and only live 1-2 years. Like all squids, they never develop any bone structure, relying on the fluid within their body cavities to support their shape (a hydrostatic skeleton), as well as their 1-metre chitinous gladius (pen).
Humboldts participate in diel vertical migration (DVL), swimming to shallower waters at night to hunt and returning to deep water at dawn. There is more potential prey available in the euphotic zone, and spending the nights in warmer shallower waters allows the Humboldt and other DVL organisms to conserve energy and heat. DVL is central to the biogeochemical process known as the oceanic carbon pump, the ongoing entrance of carbon into seawater as soluble HCO3 ions, its fixation by photosynthetic organisms and its transport to the ocean floor in the form of biomass or as carbon compounds like CaCO3. Most of this transport occurs as detritus (or "marine snow") sinking down into deep waters, but DVL organisms speed up the process by feeding on euphotic life and actively moving biomass-trapped carbon down to the deep, releasing in their waste or remains. The carbon pump is a major part of the global carbon cycle and essential to regulating atmospheric greenhouse gases; it is estimated that one-third of anthropogenic carbon emission are taken up by the ocean through the carbon pump.
Humboldt populations are still regarded as fairly healthy, and are not listed as vulnerable or endangered by the IUCN. However, they face some growing ecological challenges. Ocean acidification from increased CO2 will likely have a significant physiological effect on these squid, and the climate changes associated with the high CO2 levels may also change Humboldt behavior and restrict their depth range. In addition, noise pollution has become a major threat to Humboldts. Humboldts' statocysts are very sensitive, an adaptation that takes advantage of the ease with which sounds travels through waters. Unfortunately, these statocysts are easily ruptured by low-frequency sound, an injury resulting in the death of the organism. This could explain the massive Humboldt die-off that have been observed off the Oregon coast over the past decade.
Learn more about the Humboldt Squid:
Learn more about the Humboldt Squid:
- http://www.outsideonline.com/outdoor-adventure/science/It-s-Hard-Out-Here-for-a-Shrimp.html?page=all
- http://www.bioweb.uwlax.edu/bio203/s2012/bonis_alis/index.htm
- http://nationalzoo.si.edu/animals/invertebrates/facts/cephalopods/factsheets/humboldtsquid.cfm
- http://www.pbs.org/wnet/nature/episodes/encountering-sea-monsters/video-humboldt-squid-makes-contact/1032/
Cast your vote for the third Cephalopod of the Week! You have four choices:
- the Chambered Nautilus, a living fossil that that has survived pretty much unchanged for the past 500 million years
- The Colossal Squid, a reclusive Antarctic deep-sea dweller with the largest body mass of any cephalopod
- The Greater Blue-Ringed Octopus, a small but dangerous octopus equipped with neurotoxins that can kill humans
- The Veined Octopus, a tool-using, bipedal cephalopod (think Animal Farm pigs, but cuter)
Author: Matthew
RSS Feed
