#benthic fauna

[uncharismatic-fauna]

Hellbent on the Pacific Hagfish

Pacific hagfish, or California hagfish (Eptatretus stoutii) are one of the most well-known members of the hagfish family. They commonly seen on the ocean floor of the Pacific Ocean, at depths of anywhere between 16–966 metres (52–3,169 ft). They generally prefer muddy substrate, but may also be found on rocky outcroppings with plenty of crevices and caves. Because of their extremely low metabolism, they are also capable of surviving in zero-oxygen environments for several hours.

Like other hagfish, the Pacific hagfish has a long, eel-like body. In fact, hagfish are the only living animals that have a skull but no vertebrae. They also lack jaws, and the perpetually-open mouth is surrounded by a number of barbels. The skin is smooth, loose, and usually purple, pink, or grey. E. stoutii can reach up to 63 cm (25 in) in length; females are typically larger than males. They have very small, rudimentary eyes, and prominent nostrils.

Because they lack fully functioning eyes, California hagfish rely on a combination of smell and taste via a series of Schreiner organs along the sides of the body to detect their prey. They feed opportunistically on polychete worms, eggs, and carrion. Their primary predators are harbor seals, sablefish, and humans, which they avoid by producing large amounts of slime and tying themselves in knots.

There is little information on hagfish reproduction. Adults are thought to transition between sexes depending on the local ratio of males to females; adults with both sets of reproductive organs have also been recorded. They tend to reproduce every 2-3 years, when females lay 20-30 eggs. After hatching, the juveniles are fully independent, and become mature when they reach 42 cm (17 in) in length.

Conservation status: According to the IUCN, the Pacific hagfish is Data Deficient. Due to its habitat, there is not enough information on the species to determine population size or trends. However, they are increasingly harvested by fisheries for human consumption, which is a concern given the low reproductive rate

Photos

Masakazu Suzuki

NOAA

Martin Conlin

[realistic-studyblr]

Day 4 of exam study

[uncharismatic-fauna]

The Beloved Blackfin Icefish

The blackfin icefish (Chaenocephalus aceratus), also known as the Scotia Sea icefish, is a species of fish found in the Southern Ocean, around the Antarctic shelf. They typically reside along the bottom of the ocean closer to the sore, at depths no greater than 770 m (0.47 mi). These waters stay at around -2 °C (28 °F) all year.

Male blackfish are slightly smaller than female blackfish; the former reaches 34–40 cm (13-15 in) in length while the latter reaches 48–49 cm (18-19 in). The blackfin icefish is noted for its unique appearance. It is a scaleless fish, with a white or grey body sporting darker strikes all down its sides.

Part of this color comes from their blood, which lacks hemoglobin and is translucent in color. The icefish family are the only vertebrates in the world that lack hemoglobin. This lack severely reduces the oxygen carrying capacity of their blood; as a trade-off their blood is thinner to reduce viscosity and carries 'anti-freeze' proteins which allow the fish to survive below-freezing waters.

Spawning typically takes place in the autumn or winter. Females may only reproduce every other year due to the high energy costs of egg production. Male C. aceratus dig shallow depressions in the sand, and females lay clutches of up to 10,000 eggs. These eggs can take anywhere from 2-6 months to hatch, and during this time the males do most if not all of the guarding of the nest. After hatching, juveniles may take anywhere from 5-7 years to become fully mature.

The diet of Scotia Sea icefish consists primarily of krill, mackerel icefish, and crustaceans. Juveniles typically consume more krill than fish, and are more often found swimming in the water column, while adults stay along the ocean floor and ambush their prey. It is unknown whether they have any natural predators.

Conservation status: The IUCN considers the blackfin icefish as Vulnerable. Its primary threats are fatalities from fishing by-catch and climate change, which is increasing the temperature of its natural habitat.

Photos

Uwe Kils

Thomas Desvignes

Bill Baker

[uncharismatic-fauna]

The Novel Norway Lobster

Nephrops norvegicus, better known as the Norway lobster, the Dublin Bay lobster, or in its culinary form as langoustine or scampi, is a small lobster found all along the European coast in the Atlantic ocean, from Norway and Iceland to Portugal, as well as the Adriatic Sea. They reside in muddy seabeds at up to 800 m (0.5 mi) below the surface.

Norway lobsters spend most of their time digging, maintaining, and hiding in their burrows, which are built about 20 to 30 cm (8 to 12 in) deep in the mud. When they do leave their burrows, it is only to forage or mate. Like many lobsters, N. norvegicus is an omnivore; they feed on anything they can find, including carrion, worms, fish, jellyfish, and other crustaceans. Predators include larger crustaceans, such as shore crabs, cod, stingrays, and small spotted catsharks.

The breeding period for Dublin Bay lobsters depends on the population's location and the temperature of the water, but generally takes place in late winter or spring. Females typically mate with 2-3 males, and carries 1000-5000 eggs under her tail for 8 to 9 months. After hatching, the planktonic larvae drift through the ocean for about two months, during which time they rise to the surface at night and descend to the ocean floor during the day. After settling on the bottom, juveniles undergo a molt before becoming fully mature. Afterwards, adults typically undergo 1-2 molts every year, and can live up to 10 years in the wild.

N. norvegicus is typically pink or orange in color, with a white underbelly and a darker stripe along the upper part of the claw. Adults can reach up to 20 cm (8 in) in length including the claws, which can comprise up to half that length. Its large eyes are exceptionally sensitive to light, and Norway lobsters are rarely seen during the daytime.

Conservation status: The Dublin Bay lobster is classified as Least Concern by the IUCN. It is commonly harvested for food, and populations are monitored closely.

Photos

Sue Scott

Institute of Marine Research

Hans Hillewaert

[uncharismatic-fauna]

Scope Out the Atlantic Sea Scallop

The Atlantic Sea scallop, also known as the deep sea scallop (Placopecten magellanicus), is a species of scallop native to the North American coastline of the Atlantic Ocean, from southern Canada to the coastal plains of the mid-region United States. They primarily reside along rocky or sandy areas of the ocean floor from depths of 18–110 m (59-360 ft), although they can occasionally be found at depths as shallow as 2 m (6 ft).

The Atlantic sea scallop is characterized by its two round, smooth shells with a squared off foot. The color of this shell can vary from red or pink to brown or white, and is on average 8 cm (3.25 in) in diameter. Around the interior edge of the shell, set in a white film-like substance called the mantle, are several dozen rudimentary eyes, which are capable of perceiving light and movement. Also emerging from the mantle are a number of small tentacles which are used to filter food from their surroundings.

Deep sea scallops are filter feeders, consuming microorganisms such as phytoplankton, zooplankton, and bits of detritus which float in the water column. In turn they are predated upon by large fish such as cod and flouders, , crabs, lobsters, sea turtles, and sea stars. Their shell provides some protection from predators, and when that fails, adults are able to move from one area to another by sucking water in through their valves and then forcefully ejecting it, much like a cephalopod.

Although they are not actively social, deep sea scallops typically occur together in large numbers; these aggregations, or beds, can have densities as high as 38 individuals per square meter. Population densities may fluctuate based on food availability and reproductive status.

About 4% of the P. magellanicus population is capable of producing both male and female gametes, but the majority produce only one or the other. However, individuals have been known to change their sex several times over the course of their lives. Reproduction typically occurs in late summer and fall, from August to October, although populations may also reproduce in the spring. During spawning, males discharge their sperm into the water; these sperm are combined with the eggs held at the edge of the female's mantle. The resulting larvae are immediately released back into the open ocean. A single female may release a hundred million eggs every year, although very few survive to adulthood.

Once in the water column, the larvae float freely for 4-6 weeks. Once they begin to secrete the material that will harden into their shells, they settle on the ocean floor. They remain in one place for 2-3 years while they continue to grow in size; once they reach their adult size, at about 2 years old, they begin to roam freely in search of a bed with other adults. Individuals become sexually mature at about 4 years old, and can live up to 20 years in the wild.

Conservation status: The Atlantic sea scallop has not been evaluated by the IUCN. Although populations in some localities have been reduced or eliminated due to over-harvest for human consumption, the species is thought to have a generally large and stable population.

Photos

Dann Blackwood

Jeff Goddard

NOAA Fisheries

[uncharismatic-fauna]

Take Off with the Flying Gurnard

The flying gurnard, also known as the helmet gurnard or the Atlantic flying gurnard (Dactyloperus volitans) is a species of bottom-dwelling fish found along the tropical coasts of the Atlantic ocean, typically from Brazil to the northern United States on the western side, and from Angola to the English Channel on the eastern side. They are also commonly spotted throughout the Mediterranean Sea. Helmet gurnards prefer warm waters. They generally stay close to muddy or sandy ocean flats, although they may occasionally be seen among rocks or kelp forests.

Flying gurnards are named for their peculiar swimming motion; rather than propelling themselves with their tails, they have large wing-like pectoral fins to glide through the water when startled. When foraging, D. volitans also uses its folded up 'wings' to 'walk' along the ocean floor. They feed primarily on small fish, crustaceans and other small invertebrates found in the sand. Although they are covered in spines and thick, sheath-like scales, helmet gurnards are prey for a large variety of larger fish such as groupers, wrasse, and sharks, as well as sea birds; however, in addition to providing a quick getaway, their broad, colorful fins can make them appear bigger than they really are, startling potential predators.

On average, D. volitans reaches 50 cm (20 in) in length and 1.8 kg (4.0 lb). They are rather plain colored at first glance, usually brown or olive with light and dark spots that allow them to blend seamlessly into the ocean floor. Their most dazzling feature are their pectoral fins, which sport bright blue phosphorescent spots and a blue lining around the edge.

Flying gurnards have two spawning periods; one from May to August and another from November to February. During the spawning periods, both males and females release their respective reproductive materials (sperm and eggs) into the water, where they combine and fertilize. After hatching, the larvae will spend several months being carried by the currents before they settle down onto the ocean floor. Juveniles can reach maturity between 1-2 years old, and can live to be at least 4-5 years old in the wild, although their true lifespan has yet to be confirmed.

Conservation status: D. volitans is considered Least Concern by the IUCN. They are occasionally caught as by-catch in fishing nets.

Photos

Beck Mannjan

Thomas Menut

Stergios Vasillis

[uncharismatic-fauna]

A Stingray Abroad: The Broad Stingray

Bathytoshia lata is a stingray known by many names: the broad stingray, the brown stingray, and thorn tail stingray; Dasyatis lata, Dasyatis thetidis, and Dasyatis ushii. The species has accumulated all these names-- and quite a few others-- thanks to its broad distribution. It can be found in the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean sea. Typically the species stays on reefs or in coastal bays with muddy bottoms. Prior to 2012, genetic testing of stingray species revealed them to be populations of B. lata, hence the multitude of latin names.

The broad stingray is one of the largest species of stingrays; the average individual is about 1.5 m (5 ft) across and 56 kg (123 lb), with some populations reaching an excess of 2.6 m (8.5 ft) across and 290 kg (639 lbs). Females also tend to be larger than males. The body is diamond shaped, and the tail is often more than twice its length. B. lata is dark in color, often tan or black, with a white underbelly. Perhaps its most distinctive feature are the 'spines'-- also known as dermal denticles-- that line the tail and rear portion of the body, giving it the name 'thorn tail'.

The brown stingray is fairly docile, and spends most of the day lying inactive on the sea bed. At night they forage for crustaceans, polychaete worms, and small fish. They can use their powerful pectoral fins to burrow through the sand and uncover prey, and like sharks they have special organs called ampullae of Lorenzini that allow them to detect electrical fields emitted by their prey. The primary predator of B. lata is the hammerhead shark, and when threatened individuals will raise the spines along their tail to deliver whip-like blows.

Females become ready to mate in the summer, typically from November to March. Males are attracted to pheromones released by the female, and initiate a dance-like courtship ritual. If the female is receptive, he will bite down on her pectoral fins while grasping her with special claspers located at the base of the tail. Following the mating ritual, the female gestates her young internally for 10-12 months. This species is ovoviviparous, and the pups recieve nutirents from both a yolk and internally secreted milk. Following her pregnancy, the mother gives birth to live young, typically 3-4 in a litter. The pups are completely independent, and receive no parental care after being born. It takes them about 14-16 years to become fully mature, and individuals can live up to 28 years in the wild.

Conservation status: The broad stingray is considered Vulnerable by the IUCN. Its most common threat comes from being caught as by-catch in fishing nets, and intentionally for their meat and skin.

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Photos

Andy Murch

Sarah Speight

Andrew Green

Phillipe Guillaume

[uncharismatic-fauna]

Another Day, Another Pacific Sand Dollar

The eccentric sand dollar, aka the sea-cake, biscuit-urchin, western sand dollar, or Pacific sand dollar (Dendraster excentricus), are found in the intertidal zone and near-shore sandy bottoms from Alaska, US to Baja California, Mexico.They are the only sand dollars endemic to the Pacific Northwest, though they share the rest of their range with other species. Live individuals are seen either partially buried upright or lying flat on the ocean floor, depending on the strength of the current. To prevent themselves from being swept away, juveniles will also ingest sand to weigh themselves down. Although they are not social, they can form large colonies with as many as 6 sand dollars in a square m (1 sq yd).

Pacific sand dollars are named for their resemblance to silver dollars, especially the bleached exoskeletons that commonly wash up on beaches. Most adults average about 8 cm (3 in) across, though individuals as big as 10 cm (4 in) have been found. The body is a flat disc coated in small, purple tube-like feet and sensory organelles called cilia. The feet are used both for moving across the ocean floor and for pulling oxygen from the water. The mouth and anus-- a single opening-- are located on the sand dollar’s underside. Inside the mouth are five teeth and jaw plates known as doves; together they form a structure known as Aristotle’s lantern, which is unique to echinoderms like sand dollars and sea stars.

D. excentricus is a suspension feeder, using its feet and cilia to pull food from the water or direct it along special groves on the body’s underside. Their main prey are microscopic larvae, copepods, diatoms, algae, plankton, and detritus. The sea-cake is predated upon by a number of sea stars and fish, as well as crabs and sea gulls. To avoid being eaten, adults bury themselves in the sand and larvae will duplicate themselves via a process known as budding and fission, which creates smaller individuals that can distract potential predators.

Although western sand dollars have seperate sexes, they are broadcast spawners. In late spring or early summer, males and females congregate and release gametes into the water where they become fertilized. Larvae, also known as prisms, hatch just a day later. This larvae floats freely through the water, growing arms and metamorphosing into a echinopluteus larva. Once they reach 8 arms, the larva begins to develop an exoskeleton or echinus, and resembles a small adult. The final stage of growth is triggered by chemical cues released by other adults; after this, individuals become sexually mature and settle on the ocean with other sand dollars. In the wild, adults can live up to 13 years.

Conservation status: Although the IUCN has not evaluated the Pacific sand dollar, they are regularly threatened by ocean acidification, warming, and bottom trawling.

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Photos

Chan Siuman

Brian Starzomski

Alison J. Gong