“…and today we’re talking about an animal with a name that sounds like a AAA baseball team.”
Deep in the dark, desolate depths of the ocean, where the sun don;’t shine and the pressure is crushing, there slinks a squishy, sausage-shaped sensation. This waddler of the abyss trundles through the muck with an extremely bizarre gait. With a body like a bag of jello and a locomotion style that’s more “inflatable parade float” than anything else, the sea pig is the pinnacle of effortless grace. But when you live at the bottom of the bottom of the ocean, it pays not to care what other people think about the way you walk like the sea pig here in Life, Death, and Taxonomy.
Description
Sea pigs have a soft, round, translucent white body, with five to seven pairs of tube-like feet used for locomotion and possibly respiration. These tube feet, powered by water pressure and muscle contractions, allow them to “walk” on the ocean floor, a unique trait among holothurians.
Body Structure: Bilaterally symmetrical, with a thin body wall that sometimes reveals internal organs or parasites. The upper tube feet may serve sensory functions, though their exact role is unclear.
Measure Up
Length of Scotoplanes globosa
Scotoplanes globosa has a length of 15 cm (5.91 inches). How many sea pigs, laid end to end, fit into the length of these nautical or ocean-related objects?
Question: How many Scotoplanes globosa fit into each object’s length?
- 4 go into the length of a lionfish
- 0.5 go into the length of a sextant
- 0.8 go into the length of a deep-sea anglerfish
a) The length of a lionfish
The lionfish (Pterois volitans), an invasive species in Atlantic and Caribbean waters, reaches about 38 cm (15 inches) in length for a large adult, including fins.
b) The length of a sextant
A nautical sextant, a navigational tool used by sailors, typically measures about 25 cm (9.84 inches) along its longest frame edge for a standard 19th-century model.
c) The length of a deep-sea anglerfish
The humpback anglerfish (Melanocetus johnsonii), found in deep ocean waters, has a body length of about 12 cm (4.72 inches) for a large female, excluding the lure.
Weight of Scotoplanes globosa
Scotoplanes globosa weighs 100 grams (0.1 kg). How many sea pigs fit into the weight of these nautical or ocean-related objects?
Question: How many Scotoplanes globosa fit into each object’s weight?
A) 10.0 go into the weight of a nautical brass compass
B) 0.9 go into the weight of a green sea turtle hatchling
C) 3.0 go into the weight of a jellyfish
a) The weight of a nautical brass compass
A traditional brass ship’s compass, used for navigation on 19th-century vessels, weighs about 1 kg (1,000 grams) for a standard binnacle-mounted model.
b) The weight of a green sea turtle hatchling
A green sea turtle (Chelonia mydas) hatchling, found in tropical oceans, weighs about 25 grams (0.025 kg) at birth.
c) The weight of a jellyfish
The moon jellyfish (Aurelia aurita), common in coastal oceans, weighs about 500 grams (0.5 kg) for a large adult, including water content.
Fast Facts
Depth Range: Found at depths of 545–9,997 meters, from abyssal plains to hadal zones like the Kermadec Trench (6,659 m) and Philippine Trench (9,997 m).
Geographic Range: Cosmopolitan, present in the Arctic, Atlantic, Pacific, Indian, and Southern Oceans, including off San Diego, Chile, the Cape of Good Hope, and Antarctica. In colder Antarctic waters, they occur in shallower depths.
Behavior: Often face into ocean currents to detect nutrient-rich feeding sites, a behavior that aids in locating fresh food.
Diet and Feeding
Feeding Strategy: Deposit feeders, consuming organic detritus (“marine snow”) that sinks to the ocean floor. They prefer fresh, nutrient-rich sediments (less than 100 days old) and are known to congregate around whale falls for their high nutrient content.
Feeding Mechanism: Use mucous-covered tentacles to transfer food from the seafloor to their mouth.
Social and Ecological Behavior
Congregations: Often form groups called “trawls,” ranging from 10–30 to as many as 600 individuals, typically facing into currents to optimize feeding.
Symbiotic Relationships: About 22% of sea pigs are accompanied by Neolithodes diomedea, a lithodid crab. The relationship may be mutualistic or commensal, with crabs potentially gaining nutrients and mobility while protecting sea pigs from parasites.
Parasites: Host deep-sea parasites like gastropods (Stilapex, Crinolamia) and crustaceans, which bore into their body wall.
Reproduction and Life Cycle
Reproductive Traits: Gonochoric (separate sexes) with a single gonad. They are oviparous, with external spawning and fertilization. Some exhibit brooding. Embryos develop into planktotrophic auricularia larvae, then doliolaria, before metamorphosing into juvenile sea cucumbers.
Gametogenesis: Evidence of gamete development has been observed.
Ecological Significance
Nutrient Cycling: Sea pigs play a role in deep-sea ecosystems by consuming organic matter, with their feeding influenced by surface ocean events like El Niño, which increase food availability. Population booms have been noted after such events (e.g., 1997–1999).
Vulnerability: Deep-sea trawling poses a threat, as a single sweep can kill up to 300 individuals.
Major Fact: Tiptoeing Through the Abyss
- Sea pigs move using specialized tube feet, which are elongated, leg-like appendages powered by a water vascular system, inflating and deflating like tiny hydraulic stilts.
- These tube feet, five to seven pairs strong, allow sea pigs to “walk” across the ocean floor, a unique trait among sea cucumbers, who usually slink along with less flair.
- The tube feet operate via muscle contractions and water pressure, pushing fluid in and out to create a wobbly, deliberate stride through the deep-sea mud.
- This legged locomotion helps sea pigs navigate the soft, unstable sediment of the abyssal plain, where sinking into the muck is a real risk.
- Unlike typical sea cucumber tube feet, which are small and tucked beneath, sea pig tube feet are oversized and dorsal, doubling as possible sensory tools.
- The tube feet’s buoyancy aids in keeping sea pigs from getting bogged down, letting them hover slightly above the sediment like pudgy hovercrafts.
- Facing into ocean currents, sea pigs use their tube feet to stabilize themselves, ensuring they can sniff out fresh, nutrient-rich detritus.
- This bizarre movement style lets them efficiently scour the seafloor for organic matter, like a vacuum cleaner for whale carcasses.
- Tube feet also help sea pigs avoid being swept away by strong currents, anchoring them as they shuffle along.
- Sea pigs aerate the sediment as they trudge, boosting oxygen levels and making the seafloor more hospitable for smaller critters.
So noodle around the ocean floor, aerate your sediment, and tentatively tiptoe on tube tootsies like the sea pig here in LDT.