Chimaera

Chimaeras are cartilaginous fishes in the order Chimaeriformes, known informally as ghost sharks, rat fish (not to be confused with the rattails), spookfish (not to be confused with the true spookfish of the family Opisthoproctidae), or rabbit fish (not to be confused with the true rabbitfishes of the family Siganidae).

At one time, a "diverse and abundant" group (based on the fossil record), their closest living relatives are sharks, though in evolutionary terms, they branched off from sharks nearly 400 million years ago and have remained isolated ever since. Today, they are largely confined to deep water.Chimaeras live in temperate ocean floors down to 2,600 m (8,500 ft) deep, with few occurring at depths shallower than 200 m (660 ft). Exceptions include the members of the genus Callorhinchus, the rabbit fish and the spotted ratfish, which locally or periodically can be found at relatively shallow depths. Consequently, these are also among the few species from the Chimaera order kept in public aquaria. They have elongated, soft bodies, with a bulky head and a single gill-opening. They grow up to 150 cm (4.9 ft) in length, although this includes the lengthy tail found in some species. In many species, the snout is modified into an elongated sensory organ.

Like other members of the class Chondrichthyes, chimaera skeletons are constructed of cartilage. Their skin is smooth and largely covered by placoid scales, and their color can range from black to brownish gray. For defense, most chimaeras have a venomous spine located in front of the dorsal fin.

Chimaeras resemble sharks in some ways: they employ claspers for internal fertilization of females and they lay eggswith leathery cases. They also use electroreception to locate their prey. However, unlike sharks, male chimaeras also have retractable sexual appendageson the forehead (a type of tentaculum) and in front of the pelvic fins.The females lay eggs in spindle-shaped, leathery egg cases.

They also differ from sharks in that their upper jaws are fused with their skulls and they have separate anal and urogenital openings. They lack sharks' many sharp and replaceable teeth, having instead just three pairs of large permanent grinding tooth plates. They also have gill covers or opercula like bony fishes.

Pacific Blackdragon

1. Found in southern hemisphere, the Pacific Blackdragon lives in temperate and subtropical waters.

2. They are found in Pacific Ocean and hence the name.

3. They are deep sea creatures and are usually found at the depths of 6,562 feet or 2,000 meters from the ocean surface.

4. Though they lurk in such great depths, they still occasional swim up close to the surface while following preys like small crustaceans or small fish.

5. This fish species is known for its unusual traits. For instance, the species is sexually dimorphic. This means that the males and females are extremely different from each other not just in their looks, but also in aspects like feeding habits and lifespan.

6. The females are dominant when it comes to lifespan. Males are known to live only long enough for mating. Once they mate, the males die but females continue to live.

7. Females have fang-like teeth and chin barrels. These features are absent in males.

8. Females grow up to a length of up to 60 centimeters. In contrast, males grow up to 5 centimeters in length.

9. Females have functional guts and they use their fang-like teeth to capture prey. The males on the other hand don’t even have a functional gut.

10. Lack of teeth and gut in males mean that they don’t eat. They just grow and live until they mate. Once they mate, they die.

Terrible Claw Lobster

Dinochelus ausubeli is a small deep sea lobster discovered in 2007 in the Philippines during the Census of Marine Life and described in 2010 in the new genus Dinochelus.

Description

Dinochelus ausubeli has a carapace length of around 31 millimetres (1.2 in), and is in life mostly translucent white, with reddish pink colouring near the middle of the carapace, on the tail fan, on the antennae, and on the first pereiopods (including the claws). Its two claws are very different in size, are elongated, and bear many long teeth on the inner surface.

Distribution and discovery

D. ausubeli is only known from its type locality, 15°56′N 121°45′E, off the coast of Luzon in the Philippines. It was found by trawling at a depth of around 250 metres (820 ft) in 2007,as part of the Census of Marine Life, a major effort to document marine life in the first decade of the 21st century. It was described in 2010 by an international team of scientists.

Taxonomy

The new species was placed in a separate genus, Dinochelus, whose name derives from the Greek roots δεινός (dinos), meaning "terrible" or "fearful", and χηλή (chela), meaning "claw". The specific epithet "ausubeli" honours Jesse H. Ausubel, the sponsor of the Census of Marine Life, "in recognition of his vision and support for marine biodiversity exploration"

Dinochelus belongs to a group of lobsters previously recognised as the separate family, Thaumastochelidae, which also includes the genera Thaumastocheles andThaumastochelopsis. These genera all show very long, toothed claws with a bulbous base, with one claw much longer than the other. Dinochelus has features in common with each of those genera; on the basis of DNA sequencing using cytochrome oxidase I, Dinochelus is thought to be the sister taxon to Thaumostocheles +Thaumastochelopsis. It is distinguished from either genus by the unusual, T-shaped form of the epistome.

Tongue-Eating Louse

Cymothoa exigua, or the tongue-eating louse, is a parasitic crustacean of the family Cymothoidae. This parasite enters fish through the gills, and then attaches itself to the fish's tongue. The female attaches to the tongue and the male attaches on the gill arches beneath and behind the female. Females are 8–29 milli metres (0.3–1.1 in) long and 4–14 mm (0.16–0.55 in) in maximum width. Males are approximately 7.5–15 mm (0.3–0.6 in) long and 3–7 mm (0.12–0.28 in) wide.The parasite severs the blood vessels in the fish's tongue, causing the tongue to fall off. It then attaches itself to the stub of what was once its tongue and becomes the fish's new tongue.

C. exigua extracts blood through the claws on its front, causing the tongue to atrophy from lack of blood. The parasite then replaces the fish's tongue by attaching its own body to the muscles of the tongue stub. The fish is able to use the parasite just like a normal tongue. It appears that the parasite does not cause any other damage to the host fish. Once C. exigua replaces the tongue, some feed on the host's blood and many others feed on fish mucus. This is the only known case of a parasite functionally replacing a host organ.When a host fish dies, C. exigua will detach itself from the tongue stub after some time, leave the fish's mouth cavity, and can then be seen clinging to its head or body externally. It is not fully known what then happens to the parasite in the wild.

There are many species of Cymothoa,but only C. exigua is known to consume and replace its host's tongue.

C. exigua is quite widespread. It can be found from the Gulf of California south to north of the Gulf of Guayaquil, Ecuador, as well as in parts of the Atlantic. It has been sampled in waters from 2 metres (6 ft 7 in) to almost 60 m (200 ft) deep. This isopod is known to parasitize eight species in two orders and four families of fishes [7 species of order Perciformes: 3 snappers (Lutjanidae), 3 grunts (Haemulidae), 3 drums (Sciaenidae), and 1 species of order Atheriniformes: 1 grunion (Atherinidae)]. Females of this isopod were found in the mouths of three species of snappers. New hosts from Costa Rica include the Colorado snapper, Lutjanus colorado and Jordan's snapper, L. jordani.

In 2005, a red snapper parasitised by what could be Cymothoa exigua was discovered in the United Kingdom. As the parasite is normally found off the coast of California, this led to speculation that the parasite's range may be expanding; however, it is also possible that the isopod traveled from the Gulf of California in the snapper's mouth, and its appearance in the UK is an isolated incident.

Isopod

A giant isopod is any of the almost 20 species of large isopods (crustaceans distantly related to the shrimp and crabs, which aredecapods) in the genus Bathynomus. They are thought to be abundant in cold, deep waters of the Atlantic, Pacific and Indian Oceans.Bathynomus giganteus, the species upon which the generitype is based, is often considered the largest isopod in the world, though other comparably poorly known species of Bathynomus may reach a similar size (e.g., B. kensleyi).

French zoologist Alphonse Milne-Edwards was the first to describe the genus in 1879^[4] after his colleague Alexander Agassiz collected a juvenile male B. giganteus from the Gulf of Mexico; this was an exciting discovery for both scientists and the public, as at the time the idea of a lifeless or "azoic" deep ocean had only recently been refuted by the work of Sir Charles Wyville Thomson and others. No females were recovered until 1891.

Giant isopods are of little interest to most commercial fisheries owing to the typical scarcity of catches and because ensnared isopods are usually scavenged beyond marketability before they are recovered. The species are noted for resemblance to the common woodlouse orpill bug, to which they are related. The few specimens caught in the Americas and Japan with baited traps are sometimes seen in public aquariums.

Northern Stargazer

Astroscopus guttatus (northern stargazer) is a fish that can reach lengths of 22 inches (56 cm) and are located on the eastern shores between the states of North Carolina and New York in the United States. The northern stargazer can be found up to depths of 120 feet (37 m). Stargazers have a flat forehead with a lot of body mass up front near the mouth.

Description

The northern stargazer has a blackish brown body with white spots that are of the same size all over its head and back. It has three dark horizontal stripes on its (white) tail. The mouth of the stargazer faces up so that it can ambush prey while hiding in the sandy bottoms of coastal bodies of water. The top of the stargazer has electric organs in the orbitae ^[1] which can generate and transmit an electric shock.

Ecology

The northern stargazer lives primarily along the eastern seaboard of the United States. They bury themselves in the sand and wait for prey (usually smaller fish) to come by.Their eyes are situated on top of the head and poke up through the sand, hence the name stargazer. Stargazer's scientific name is Astroscopus guttatus where Astroscopus means "one who aims at the stars" and guttatustranslating into "speckled" – referring to the white spots on the fish's back.

Life cycle

The stargazer lays small, transparent eggs on the bottom of the bay. These eggs float to the surface after they are released. They hatch into larvae and grow up to 6–7 mm (0.24–0.28 in). They slowly grow a dark coloring and develop the electrical organs from eye muscles when they are 12–15 mm (0.5–0.6 in). After this they swim to the bottom and grow into adults.

Anglerfishes

Anglerfishes are fish of the teleost order Lophiiformes .They are bony fish named for their characteristic mode of predation, in which a fleshy growth from the fish's head (the esca or illicium) acts as a lure.

Some anglerfish are also notable for extreme sexual dimorphism and sexual parasitism of the small male on the much larger female, seen in the suborder Ceratioidei. In these species, males may be several orders of magnitude smaller than females.

Anglerfish occur worldwide. Some are pelagic, while others are benthic; some live in the deep sea (e.g., Ceratiidae), while others on the continental shelf (e.g., the frogfishes Antennariidae and the monkfish/goosefish Lophiidae). Pelagic forms are most laterallycompressed, whereas the benthic forms are often extremely dorsoventrally compressed (depressed), often with large upward-pointing mouths.

Sarcastic Fringehead

The sarcastic fringehead, Neoclinus blanchardi, is a small but ferocious fish which has a large mouth and aggressive territorial behavior, for which it has been given its common name. When two fringeheads have a territorial battle, they wrestle by pressing their distended mouths against each other, as if they were kissing. This allows them to determine which is the larger fish, which establishes dominance.

They can be up to 30 centimetres (12 in) long, elongate and slender,and are mostly scaleless with great pectoral fins and reduced pelvic fins. They tend to hide inside shells or crevices. After the female spawns under a rock or in clam burrows the male guards the eggs.

They are found in the Pacific, off the coast of North America, from San Francisco, California, to central Baja California. Their depth range is from 3 to 73 metres (10 to 240 ft).

barreleye fish

Researchers at the Monterey Bay Aquarium Research Institute recently solved the half-century-old mystery of a fish with tubular eyes and a transparent head. Ever since the “barreleye” fishMacropinna microstoma was first described in 1939, marine biologists have known that it’s tubular eyes are very good at collecting light. However, the eyes were believed to be fixed in place and seemed to provide only a “tunnel-vision” view of whatever was directly above the fish’s head. A new paper by Bruce Robison and Kim Reisenbichler shows that these unusual eyes can rotate within a transparent shield that covers the fish’s head. This allows the barreleye to peer up at potential prey or focus forward to see what it is eating.

Deep-sea fish have adapted to their pitch-black environment in a variety of amazing ways. Several species of deep-water fishes in the family Opisthoproctidae are called “barreleyes” because their eyes are tubular in shape. Barreleyes typically live near the depth where sunlight from the surface fades to complete blackness. They use their ultra-sensitive tubular eyes to search for the faint silhouettes of prey overhead.

Although such tubular eyes are very good at collecting light, they have a very narrow field of view. Furthermore, until now, most marine biologists believed that barreleye’s eyes were fixed in their heads, which would allow them to only look upward. This would make it impossible for the fishes to see what was directly in front of them, and very difficult for them to capture prey with their small, pointed mouths.

Robison and Reisenbichler used video from MBARI’s remotely operated vehicles (ROVs) to study barreleyes in the deep waters just offshore of Central California. At depths of 600 to 800 meters (2,000 to 2,600 feet) below the surface, the ROV cameras typically showed these fish hanging motionless in the water, their eyes glowing a vivid green in the ROV’s bright lights. The ROV video also revealed a previously undescribed feature of these fish–its eyes are surrounded by a transparent, fluid-filled shield that covers the top of the fish’s head.arreleyes share their deep-sea environment with many different types of jellies. Some of the most common are siphonophores (colonial jellies) in the genus Apolemia. These siphonophores grow to over 10 meters (33 feet) long. Like living drift nets, they trail thousands of stinging tentacles, which capture copepods and other small animals. The researchers speculate that barreleyes may maneuver carefully among the siphonophore’s tentacles, picking off the captured organisms. The fish’s eyes would rotate to help the fish keep its “eyes on the prize,” while its transparent shield would protect the fish’s eyes from the siphonophore’s stinging cells.

Robison and Reisenbichler hope to do further research to find out if their discoveries about Macropinna microstoma also apply to other deep-sea fish with tubular eyes. The bizarre physiological adaptations of the barreleyes have puzzled oceanographers for generations. It is only with the advent of modern underwater robots that scientists have been able to observe such animals in their native environment, and thus to fully understand how these physical adaptations help them survive.

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Video of barreleye narrated by Bruce Robison:

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Research paper:

B. H. Robison and K. R. Reisenbichler. Macropinna microstoma and the paradox of its tubular eyes. Copeia. 2008, No. 4, December 18, 2008.

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