Macroramphosus scolopax (Linnaeus, 1758)

Coloration

Longspine snipefish, Macroramphosus scolopax, have a reddish pink back and silvery belly.

Head and Dorsal Traits

They feature large eyes, long snouts, and a slender spine that protrudes from their dorsal side.

Overall Body Length Range

Total body length of this species ranges from 4.8 to 16.0 cm (1.9 to 6.3 in).

Mature Individual Size by Sex

For mature individuals, males range from 9.1 cm to 13.8 cm with a mean length of 11.74 cm, while females are slightly larger, ranging from 9.7 cm to 16.0 cm with a mean of 13.12±1.743 cm.

Males also have a slightly shorter postocular head length than females.

First Dorsal Fin Spine Length

A key prominent trait is the second spine in the first dorsal fin, which measures between 21.92 mm and 36.47 mm.

Morphological Variation Overview

This species shows wide morphological variation.

Identified Morphological Types

Research by Barbara Zorica and Nedo Vrgoč identified three distinct morphological types: the scolopax type, the gracilis type, and the intermediate type.

Scolopax Morphotype Traits

The scolopax type has a deep body, a long serrated dorsal spine, and brick reddish color.

Gracilis Morphotype Traits

In contrast, the gracilis type has an elongated body, a shorter non-serrated dorsal spine, and bluish-grey color.

Intermediate Morphology Range

A full series of intermediate forms exist between these two extreme morphologies.

Sexual Dimorphism Observations

The study found no observable external sexual dimorphism, though researchers could identify females by the presence of a dark genital papilla and a swollen abdomen.

Male Courtship Color Changes

Males are known to develop temporary color changes during courtship, growing darker ventral areas and red patterns that fade quickly if the fish are disturbed or fed.

Morphotype Feeding Group Hypothesis

In a separate study, Thomas A. Clarke proposed that the two primary morphotypes correspond to different feeding groups: the scolopax type is a benthic feeder, while the gracilis type is planktivorous.

Planktivorous Morphotype Traits

Planktivorous individuals have relatively longer snouts, more slender bodies, shorter second dorsal spines, and smaller eyes.

Benthic Feeding Morphotype Traits

Benthic feeding individuals have shorter snouts, deeper bodies, longer dorsal spines, and larger eyes.

Morphotype Naming Consistency Across Studies

Even though the two studies used different naming systems, the gracilis type matches Clarke’s planktivorous type, and the scolopax type matches Clarke’s benthic feeding type, which is the deeper-bodied form with longer spines.

Sympatric Species Classification Proposal

Further research conducted at the Great Meteor Seamount supports classifying the two feeding and morphological types as separate sympatric species within the Macroramphosus scolopax complex.

Gracilis Morphotype Juvenile Hypothesis Rejection

This study also rejected the hypothesis that the gracilis type is simply the juvenile stage of the scolopax type, since all measured gracilis specimens were larger than scolopax specimens in this sample.

Portuguese Waters Study Findings

Another study of samples collected in Portuguese waters also suggests that Macroramphosus scolopax may contain two distinct species, though the study’s author notes that additional research is needed to confirm whether reproductive isolation exists between the morphotypes and to validate this reclassification.

Global Distribution Range

This fish is found worldwide in tropical to subtropical waters across the Atlantic, Indian, and western Pacific Oceans.

Eastern Pacific Distribution Record

It has also been recorded in the eastern Pacific near Santa Catalina Island, California.

Latitudinal Occurrence Range

It occurs most commonly at temperate latitudes between 20–40°N, but can also be found in the southern hemisphere as far south as 43°S.

Depth Habitat Preferences

It typically inhabits depths from 25 to 600 m (82 to 1,969 ft), and shows a clear preference for depths over 100 meters, especially favoring deeper areas of the continental shelf and continental slope.

Pre-Courtship Male Coloration

Males change color before courtship to attract females: their brownish ventral area and the base of the dorsal spine darken, while the posterior part of the body turns brick red.

this dark coloration extends forward along the back and sides.

Courtship Color Fade Response

The entire color pattern can fade within seconds if the fish are startled.

Male-Male Aggression Context

During the courtship period, males show aggressive behavior toward each other, and these fights are tied to gaining access to mating opportunities.

Competing Male Swimming Posture

Longspine snipefish normally maintain a head-down posture, but two competing males will instead swim parallel toward each other, abandoning the typical head-down position.

Parallel Swimming Signaling Function

This parallel swimming acts as a signaling behavior before actual competition begins.

Dorsal Spine Strike Behavior

A common aggressive behavior between courting males is striking an opponent with an erect dorsal spine: an attacking male swims rapidly toward the rival, turns its back toward the other fish, and strikes with the raised dorsal spine.

Post-Strike Attacking Male Behavior

After the strike, the attacking male swims away to gain distance to improve its aim and speed for the next charge.

Attacked Male Defense Behavior

The attacked male usually stays stationary in a head-down position and may roll its body to reduce the area exposed to attack.

Courtship Timing and Initial Location

Courtship takes place in the late afternoon, starting when the fish are near the seabed.

Initial Male Courtship Behavior

Courting males follow and swim parallel to the female near the bottom while holding a head-down position.

Female Courtship Response

When the male moves close enough, the female erects her dorsal spine.

Male Position Adjustment During Courtship

The male follows the female’s movements, frequently switching position from one side of the female to the other.

Pre-Ascent Courtship Positioning

Next, the male slowly bends his caudal peduncle toward the female at a 90-degree angle, and the female moves her abdomen toward the male.

Courtship Ascent Initiation

The two fish join by their caudal peduncles, and then swim together upward toward the water surface.

Fertilization During Ascent

During this ascent, the female’s genital papilla extends and makes repeated contact with the male’s genital region.

Egg release and fertilization both occur during this upward movement.

Post-Spawning Behavior

Once the fish reach the surface, they separate and return to the bottom.

Study Limitation Note

The author of this observational study suggested that the duration of the ascent and its endpoint at the surface may be influenced by experimental conditions, specifically the limited depth of the tank used for observation.