''Assessor macneilli'', the blue devilfish or blue scissortail, is a fish from the southwest

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

Ocean. It occasionally makes its way into the aquarium trade. It grows to in length. It is purple-blue with long fins.

Description

''Assessor macneilli'' is a dark blue fish which has a thin paler blue edge on the

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

anal Anal may refer to: Related to the anus *Related to the anus of animals: ** Anal fin, in fish anatomy ** Anal vein, in insect anatomy ** Anal scale, in reptile anatomy *Related to the human anus: ** Anal sex, a type of sexual activity involving ...

, and

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s. The dorsal fin has 11 spines and 8–10 rays, the anal fin has 3 spines and 9–10 rays and the

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

s have 14–16 rays.

Distribution

The blue devilfish is found in the western Pacific Ocean from north eastern Australia and New Guinea, through the

Great Barrier Reef The Great Barrier Reef is the world's largest coral reef system, composed of over 2,900 individual reefs and 900 islands stretching for over over an area of approximately . The reef is located in the Coral Sea, off the coast of Queensland, ...

and the

Coral Sea The Coral Sea () is a marginal sea of the Pacific Ocean, South Pacific off the northeast coast of Australia, and classified as an Interim Biogeographic Regionalisation for Australia, interim Australian bioregion. The Coral Sea extends down t ...

New Caledonia New Caledonia ( ; ) is a group of islands in the southwest Pacific Ocean, southwest of Vanuatu and east of Australia. Located from Metropolitan France, it forms a Overseas France#Sui generis collectivity, ''sui generis'' collectivity of t ...

Habitat and biology

''Assessor macneilli'' is found on reefs at depths of , where it can group together in shoals of up 100 fishes in caves, crevices and under ledges, where they often swim upside down. It is a

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

feeder and its main food are

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s such as

copepods Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (living in the water column), some are benthic (living on the sediments), several species have ...

ostracods Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant) have been identified,Brandão, S.N.; Antonietto, L.S; Nery, D.G.; Santos, S.G.; Karano ...

and

amphipods Amphipoda () is an order (biology), order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphip ...

. It is a

mouthbrooder Mouthbrooding, also known as oral incubation and buccal incubation, is the care given by some groups of animals to their offspring by holding them in the mouth of the parent for extended periods of time. Although mouthbrooding is performed by a va ...

and the male guards the eggs in his mouth for 15–16 days, as hatching approaches the male keeps his mouth open continually and shifts the eggs backwards and forwards every 2–8 minutes.

Naming

''Assessor macneilli'' was described in 1935 by G.P. Whitley from specimens collected at

Hayman Island Hayman Island is the most northerly of the Whitsunday Islands, off the coast of Queensland, Australia. The island is and lies to the north-west of Hook Island. It is a private island open to the public, most famous for its luxury resort which ...

in the

Whitsunday Passage The Whitsunday Islands are 74 continental islands of various sizes off the central coast of Queensland, Australia, north of Brisbane. The northernmost of the islands are off the coast by the town of Bowen, while the southernmost islands are ...

off

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

. Whitley did not set out why he chose the name but it is thought that the genus name ''Assessor'' means assistant or helper and that the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

refers to Whitley's colleague, the

carcinologist This is a list of notable carcinologists. A carcinologist is a scientist who studies crustaceans or is otherwise involved in carcinology (the science of crustaceans). References

{{Reflist, 24em Carcinologists, . Lists of zoologists, Carcino ...

Francis A. McNeill of the

Australian Museum The Australian Museum, originally known as the Colonial Museum or Sydney Museum. is a heritage-listed museum at 1 William Street, Sydney, William Street, Sydney central business district, Sydney CBD, New South Wales. It is the oldest natural ...

. McNeill probably assisted Whitley in his

ichthyological Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

collections.

References

{{Taxonbar, from=Q590024 macneilli Fish described in 1935