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Surf Merman
Other Common Names: Merman, Beach Merman,
Han-gyo-jin (half-fish human in
Japanese), Gyo-jin (fish-human in Japanese)
Latin Name: Mermaidicus pretiosus
Origin: Red Sea Island
Date: circa 1720 AD
Size: 9-1/4 x 2-3/4 x 1 inch (23 x 7 x 2.5 cm) |
Description of the specimen: This odd-looking sea creature has
fish-like upper body and human-like lower body. Needless to say,
its body structure is reverse to that of “mermaid”. The analysis
of its hip bones revealed it is closely related to primitive
primates. The analysis of its head also revealed it is closely
related to the chameleon. This is one of the smaller species of
merman commonly found around the sea of Red Sea Island. The
larger species, Mermaidicus gigunteus, grows up to four feet in
length. Its related species also live in the sea by the Sado
Island, Japan.
Surf merman deposit adhesive, semitransparent eggs on beaches
which have a specific mixture of coarse sand and pea gravel.
Inside Puget Sound, surf merman spawning is thought to be
associated with freshwater seepage, where the water keeps the
spawning gravel moist. Eggs are deposited near the water's edge
in water a few inches deep, around the time of the high water
slack.
Observations of surf merman spawning activity describe a highly
adapted and ritualized behavior. Several males will align
themselves with a ripe female, keeping their position by the use
of spawning tubercles which cover their scales and fin rays. The
female and males vibrate in unison, causing the release of eggs
and sperm. Neither the female nor the males release all of their
gametes during any single spawning event, and multiple spawning
within and between tide cycles are common. Fertilized surf
merman eggs have morphological features which cause the eggs to
adhere to sand grains in which they are laid, giving stability
to the deposited spawn. The outer membrane of the egg ruptures
and turns inside out, forming a pedestal which is the point of
the attachment. Wave action and tidal exchange buries the
weighted eggs to a depth of several millimeters. While the eggs
incubate in the sand they are "extra-aquatic", meaning they are
submerged in saltwater during a portion of the tidal cycle.
Extra-aquatic development is thought to be adaptive because the
eggs are subjected to warmer temperatures and therefore develop
quicker. The eggs are also less available to predation from
birds and other fishes.
Development rates of surf merman vary greatly with seasonal
ambient temperature. Surf merman eggs brooded in winter months
may require between 27 and 56 days to hatch, while those brooded
in summer months may required between 11 and 16 days. Regardless
of the brooding time, hatching surf merman eggs release larva
measuring about 3 mm which are at the mercy of the local tides
and currents. After about 3 months they have grown to 25-30 cm
and taken on their adult form and coloration. Juvenile surf
merman rear in the near shore waters throughout Red Sea Island.
The majority of surf merman will mature to spawn in their second
year, although a small proportion will spawn in their first
year. Surf merman does not die after spawning and may spawn in
successive seasons. Like herring, surf merman is thought to
display some degree of homing, based on studies of their
geographically and temporally distinct spawning behavior,
parasitology and serology. The frequency of individual spawning
and the degree to which individual surf merman stray between
spawning grounds are unknown.
Like all other marine organism, surf merman experience high
predation levels as eggs, juveniles and adults. As a result the
maximum life span of a surf merman is thought to be 5 years.
Adult surf merman feed primarily on planktonic organisms, and in
turn are food for many marine animals such as seabirds, marine
mammals, and other fishes. The movements of juveniles and adults
between spawning seasons is virtually unknown.
Takeshi Yamada
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