marine biology

“The pelagic zone is the water column in the open ocean, rather than near the coast or the sea floor.

  • The top layer (from the surface down to 200 metres), where sunlight penetrates, is known as the epipelagic zone.
  • The middle layer (200 to 1,000 metres) is the mesopelagic.

Almost all ocean life is part of a huge food web linked to the epipelagic zone. This is where microscopic plant organisms, known as phytoplankton, convert sunlight into food. Phytoplankton are eaten by zooplankton, tiny animals which are in turn eaten by other creatures. At the top of this food web are oceanic fish.” -X

[Wikipedia: Pelagic zone]

Spiny lobster tapping my camera. Its kind of cute- in a way that makes me regret ever eating lobster.



If I lived in the deep, dark sea, in the open water column of the mesopelagic habitat, I would want to have eyeballs that took up nearly 50% of my body. Okay, maybe not. It might be hard for me to swim. Then again, the hyperiid amphipod, Paraphronima gracilis, apparently thrives with giant eyes that dominate nearly half its body. And it’s not just that the eyes are gigantic, they are weird, too. This animal has a configuration of compound eyes that has never been described before. Today in Current BiologyKaren Osborn, Sonke Johnsen, and I describe the strange eyes ofParaphronima gracilis and discuss the possible advantages of their novel design.

Paraphronima has a pair of bilobed apposition compound eyes. There is a large upward-facing portion and a smaller lateral-facing portion. Having four eyes isn’t unusual in the mesopelagic habitat, especially amongst the hyperiid amphipods. The unique aspect of the eyes is the multiple, discontinuous retinas. There are 12 retinal groups in each upward-facing portion and 5 retinal groups in the lateral portions, although there is one large, dominating group in the lateral portion. In most animals with compound eyes, the retina is one continuous sheet of photoreceptors, supporting cells and screening pigments.

We suspect the unique eyes of Paraphronima are acting to maximize light capture (and therefore, vision) in the mesopelagic habitat. The mesopelagic habitat could be considered an extreme habitat. In the deep water column, away from surface, shore, or ocean bottom, there are no physical objects to hide amongst, except other animals. Light is dim and blue, extinguished to pitch black after 1000 meters. Bioluminescence flashes and search lights become the major sources of illumination. Animals here are challenged to see, without being seen. 

The eyes of Paraphronima are large and nearly transparent, with the exception of the small, orange retinas. The ommatidia of the eyes are arranged in rows perpendicular to the body axis. A single row of ommatidia may function together to boost the light gathering ability of the eye, using a process called spatial summation. In most other animals using spatial summation, a circular group of ommatidia may pool the light signal, boosting light sensitivity at the cost of spatial resolution. In Paraphronima,summation may occur in a linear, not circular, fashion. Spatial summation in one axis would allow the eye to gather more light, while reducing the cost to spatial resolution in one axis.  We suspect that Paraphronima is mainly concerned with detecting linear appearing targets, like small siphonophores which could easily be targeted in a single axis…..


A small Japanese puffer fish is the creator of one of the most spectacular animal-made structures. To impress the female puffer fish, the male labors 24 hours a day for a week to create a pattern in the sand. If the female finds his work satisfactory, she allows him to fertilize her eggs. She then lays them in the middle of the circle, leaving the male to guard the eggs alone.

Life Story (2014)


Mimic Octopus

This sea creature can mimic the behaviors and various shapes of different animals it sees. They are highly intelligent and use their ability to camouflage and avoid predators. It is so intelligent that it will actually mimic a sea creature that its predators is afraid of. For example, scientists observed that when the octopus was attacked by territorial damselfishes, it mimicked the banded sea snake, a known predator of damselfishes.

It can mimic sea creatures like the sole fish, lion fish, sea snakes, frog fish and more.


The environmental impact of oysters, in one photo

The water in both tanks came from the same source. The one on the right has bivalves. Not only do oysters naturally filter the waters in which they live, they can even protect humans from destructive hurricanes. For more, read about New York’s efforts to bring back oyster populations in the once-toxic Hudson River.

Delicious AND helpful. Who knew?

(photo via Steve Vilnit on Twitter)


photos by matt smith from the Illawarra coast in new south wales of bluebottles, violet snails and blue dragons. 

despite its resemblance to the jellyfish, the bluebottle is more closely related to coral. known as a zooid, the bluebottle (or portugese man of war) is a colonial animal composed of many highly specialized and physiologically integrated individual organisms incapable of independent survival. 

the blue dragon — a type of nudibranch, here no larger than a thumbnail, with its own potent sting — is able to eat the nematocysts (stinging cells) of the bluebottle without discharging them and internally relocate them to the tips of each one of the fingers you can see in the pictures.

for their part, the violet snails also feed on the bluebottles.

notes matt, “despite their potentially dangerous sting, the bluebottle is an amazingly beautiful creature. with strong winds, hundreds of these cnidaria are blown into the bays around my home town and trapped overnight.”

this allows him to capture the above shots, which he creates with use of a fluorescent tube in his strobe light and a homemade waterproof lens dome.


Southern fur seal pups in Kaikoura (NZ) have figured out a way to avoid taking their first swim in predator-filled waters. By travelling up a nearby stream, they reach a secluded waterfall pool where they can learn vital swimming skills in complete safety. A pup makes this journey only once, spending 3 days in the pool before returning to the sea with its newfound skills.

Life Story (2014)


Reaching sizes of at least 16 inches (40 cm), the Spanish Dancer is the largest nudibranch and one of the largest sea slugs on the planet.

Like most nudibranchs, the Spanish Dancer is brightly colored and does not blend in well with its surroundings. This bright coloration, similar to that of the poison dart frogs and many other species, serves as a warning to potential predators that the Spanish Dancer does not taste good and may even make a predator sick. Though this species spends most of its time crawling along the reef surface, it will swim when threatened, violently flapping its external gills and other appendages and displaying its brightest warning colors. This behavior reminded some observers of a flamenco dancer, earning the Spanish Dancer its common name.

via //photo 1: Mauritius100 //photo 2: manaphoto



NASA time lapse simulation showing sea surface currents around western Europe. The visualization covers 11 months, from16 February ‘05 to 16 January ‘06. with each second in the video representing 2.75 days. The different colours represent current depths - white flows are nearest the surface, and darker colours running deeper.