#seafloor

[unbfacts]

In Australia, scientists attached small cameras and trackers to endangered Australian sea lions to map parts of the ocean floor. As the sea lions swam and hunted, they filmed reefs, sand plains, sponge gardens, and other habitats that humans had not mapped well.

[todropscience]

BOTTOM TRAWLING RELEASES HIDDEN CO₂ FROM THE SEAFLOOR

A new study reveals that bottom trawling, an industrial fishing practice that drags heavy nets across the seafloor, may significantly reduce the ocean's capacity to absorb carbon dioxide (CO₂). When sediment is resuspended by trawling, storms, or tides, it exposes previously buried compounds like pyrite (FeS₂) to oxygen. The oxidation of pyrite releases CO₂ into the water, contributing to the ocean’s carbon flux and potentially adding to atmospheric greenhouse gases.

Until now, most research had focused on how disturbing organic carbon in sediments accelerates its remineralization into CO₂. This new research, however, highlights that the oxidation of pyrite, a sulfur-based mineral, could be an even greater source of carbon dioxide from the seafloor. Since fine-grained sediments rich in pyrite are widespread on continental shelves, many of which overlap with commercial fishing zones, the implications are global.

This finding underscores an urgent need to reconsider bottom trawling practices, not only for their ecological impacts but also for their role in climate dynamics. Marine protected areas and bottom trawling bans could play a vital role in preserving the ocean's function as a carbon sink. As the climate crisis intensifies, protecting the seafloor may prove as important as conserving forests.

Main photo: Tube worms and brittle stars thriving in mud bottom. Photo Oceana

Reference: Kalapurakkal et al., 2025. Sediment resuspension in muddy sediments enhances pyrite oxidation and carbon dioxide emissions in Kiel Bight. Communications Earth & Environment

[fishyy-stims]

Flying gurnard | source 🐟

[louivi]

Fiski's Seafloor Abode 🌊

[sitting-on-me-bum]

The red hydrocorals found by researchers cover about 28.5% of the seafloor of Angostura Toms, a sound in the Strait of Magellan.

Mauricio Altamirano

[geologyin-blog]

China Launches Vessel to Drill 11km into Earth’s Mantle

China's recently commissioned deep-ocean drilling vessel, Meng Xiang , has begun operations in previously unexplored regions, drilling to de

China's recently commissioned deep-ocean drilling vessel, Meng Xiang, has begun operations in previously unexplored regions, drilling to depths of up to 11,000 meters (36,000 feet) beneath the seafloor. Its mission is to penetrate the Earth's crust and reach the mantle.

[alizera62quartz]

Deep Sea Green Mermaid Alizera~

🧜‍♀️💚💎

[400millionyears]

Nurse Shark

Ginglymostoma cirratum

Family: Ginglymostomatidae

The nurse shark is a robust, slow-moving, bottom-dwelling shark, instantly recognizable by its distinctive barbels and rounded fins. It is one of the most common sharks in the tropical and subtropical waters of the Atlantic Ocean.

Physical Description and Size

The nurse shark has a robust, cylindrical body with a broad, flattened head and a blunt snout.

Adults display a yellowish-brown to greyish-brown coloration, occasionally marked with small dark spots. Juveniles, by contrast, exhibit a distinctive spotted pattern of dark spots encircled by lighter rings — a trait that gradually fades with age.

Its two rounded dorsal fins are distinctive, the first being significantly larger than the second. Long, whisker-like barbels positioned near the nostrils function as sensory organs for detecting prey. The small mouth, located well in front of the eyes, is uniquely adapted for suction feeding, and tiny spiracles sit just behind the eyes.

Size and Weight: ◦ Length: Maximum documented length is 3.08 meters. ◦ Weight: Maximum weight is approximately 110 kg.

Distribution and Habitat

The nurse shark has a wide but patchy distribution in tropical and subtropical waters of the Atlantic Ocean.

◦ Western Atlantic: From Rhode Island (USA) to southern Brazil, including the Gulf of Mexico, the Bahamas, and the Caribbean Sea. ◦ Eastern Atlantic: From Cape Verde to Gabon, and occasionally north to France. ◦ Eastern Pacific: Once considered part of the same species, Pacific populations are now recognized as a separate species: Ginglymostoma unami.

It is primarily an inshore, bottom-dwelling species, found on rocky and coral reefs, sand flats, seagrass beds, mangrove channels, and continental shelves.

Behavior and Diet

The nurse shark is a nocturnal predator distinguished by a specialized suction-feeding method and notably social resting habits.

During daylight hours, nurse sharks spend the vast majority of their time in an extremely sedentary state — resting on sandy bottoms, under rocky ledges, or packed together inside crevices in groups of up to 40 individuals, occasionally piling on top of one another. This motionless behavior is possible because, unlike species that must swim continuously to ventilate their gills, nurse sharks use buccal pumping: actively opening and closing their mouths to draw water over the gill surfaces.

At night, these same groups disperse into solitary hunters. When capturing prey, they employ powerful suction feeding, generating vacuum forces ranked among the strongest recorded for any aquatic vertebrate — capable of drawing prey directly out of tight burrows and reef crevices. For items too large to swallow whole, they use a "suck-and-spit" technique, repeatedly drawing in and expelling food until it breaks apart, or violently shake their heads to tear it into manageable pieces.

Diet: ◦ Primary: Small fish (stingrays, catfish, mullets, puffers), crustaceans (lobsters, crabs, shrimp), and mollusks (octopus, squid, snails, bivalves). ◦ Secondary: Sea urchins, sea snakes, tunicates, and algae.

Reproduction and Life Cycle

The nurse shark is ovoviviparous (aplacental viviparous): eggs hatch inside the female's body and pups are born live without a placental connection. It follows a biennial reproductive cycle — females breed every two years because the ovaries require approximately 18 months to produce a new batch of eggs, followed by a gestation period of roughly 5 to 6 months. Litter sizes typically range from 20 to 30 pups, and newborns measure approximately 27 to 30 cm in length, displaying the same spotted pattern that gradually fades with age.

Nurse sharks commonly engage in multiple paternity, meaning a single litter may have more than one father — a mechanism that enhances genetic diversity within the population. Males reach sexual maturity at approximately 200 to 210 cm in length, after 10 to 15 years; females mature later, at 240 to 260 cm, typically between 15 and 20 years of age. Once mature, wild individuals generally live between 25 and 35 years.

Relationship with Humans

Nurse sharks are generally considered harmless and docile, posing no significant danger to humans unless provoked or harassed. However, their calm temperament can lead divers to become incautious, and bites do occur — particularly where sharks have been conditioned to associate humans with food through regular feeding by tour operators. Nurse sharks should never be hand-fed, grabbed, or disturbed.

Bites are rarely deep due to the species' small teeth, typically causing only superficial skin damage. FishBase classifies the nurse shark as "traumatogenic" — capable of causing injury but not a persistent threat to human life.

⚠️Conservation Status

The International Union for Conservation of Nature (IUCN) classifies the nurse shark as Vulnerable globally. However, regional assessments vary significantly:

◦ United States and The Bahamas: Considered Least Concern. ◦ Western Atlantic (South America, Central America, Caribbean): Considered Near Threatened due to threats and population declines.

Primary threats include targeted fishing, bycatch, habitat loss, and the species' inherently slow life history.

Conservation Efforts: The nurse shark has been granted full protection from fishing in Belize since 2012, providing a vital regional refuge. Marine Protected Areas (MPAs) play a critical role in safeguarding key habitats such as coral reefs, seagrass beds, and mangroves. Ongoing population studies focusing on home ranges, seasonal migrations, and local ecology provide essential data to guide management decisions. Scientific work in Belize estimates a local population of 3,800 to 14,400 individuals, with the highest densities recorded at atolls furthest from the mainland. Because nurse sharks adapt well to public aquariums and reproduce readily in captivity, successful breeding programs help satisfy public demand while reducing collection pressure on wild populations.

🦈Fascinating Facts

Unlike fast-swimming species such as makos or great whites, which must swim continuously to breathe, nurse sharks rest motionless on the seafloor and actively pump water over their gills through buccal pumping — a trait that makes them particularly easy to observe and study.

Nurse sharks display exceptional site fidelity, returning to the same caves and crevices day after day. Tagging studies have documented individuals using the same resting sites repeatedly over multiple years — a degree of routine that is unusual among sharks.

During the day, nurse sharks frequently aggregate in groups of up to 40 individuals, sometimes piling on top of one another in shallow reef shelters. At night, this same group disperses entirely, each shark heading off to hunt alone.

Florida Museum - Nurse Shark Animal Corner - Nurse Shark National Geographic - Nurse Shark