Copyright
Richard Lydekker.

The new natural history (Volume 5) online

. (page 39 of 62)
Online LibraryRichard LydekkerThe new natural history (Volume 5) → online text (page 39 of 62)
Font size
QR-code for this ebook


body, while the pectorals formed a pair of backwardly-directed tapering spines.
True Horse- In the typical genus Caranx the body is generally more or less

Mackerels, compressed, although sometimes almost cylindrical ; the hard dorsal




COMMON MACKEREL AND HORSE-MACKEREL



fin, which may be rudimentary, is continuous, with about eight weak spines : while
in a few species the soft portion of both this and the anal is broken up into finlets.
The scales are very small; and while in the British horse-mackerel (/'. trachurust),
represented in the lower figure of our illustration, the lateral line is protected by
bony plates throughout its entire extent, in many other species these plates are
restricted to its hinder moiety. Several of these plates may be traversed by a keel
terminating in a spine. The genus is represented by nearly a hundred species,
some of which have teeth on the palate, while in others these are wanting. Rang-
ing over almost all temperate and tropical seas, many of them swim out to
considerable distances from the shore, and thus acquire a very large distributional
area. The larger forms may measure fully a yard in length : and the flesh of all



PILOT-FISH.



365



is edible. The genus is represented in the Monte Bolca Eocene. Horse-mackerel
sometimes make their appearance in enormous shoals on the British coasts ; and it
is stated that on one occasion upwards of ten thousand were taken in Cornwall.
A correspondent of Yarrell wrote, that in the summer of 1834 vast shoals of these
fish were seen on the Glamorganshire coast. " They were first observed in the
evening, and the whole sea, as far as we could command it with the eye, seemed in
a state of fermentation with their numbers. Those who stood on some projecting
rock had only to dip their hands into the water, and with a sudden jerk they
might throw up three or four. The bathers felt them come against their bodies,
and the sea, looked on from above, appeared one dark mass of fish. Every net was
immediately put in requisition ; and those which did not give way from the weight,
were drawn on shore laden with spoil. One of the party who had a herring-seine
with a two-inch mesh was the most successful; every mesh held its fish, and
formed a wall that swept on the beach all before it. The quantity is very iriade-




Pilot-Fish.



quately expressed by numbers, they were caught by cart-loads. As these shoals
rere passing us for a week, with their heads directed up channel, we had the
opportunity of noticing that the feeding-time was morning and evening. They were
sursuing the fry of the herring, and I found their stomachs constantly full of them."
Another genus is represented by the pelagic pilot-fish (Naucrates
ductor), which takes its name from a supposed habit of guiding and
protecting the sharks and ships which it accompanies. Having no plates on the
lateral line, this fish is further characterised by the rounded under surface of the
body, by the first dorsal fin being composed in the adult of detached spines, by the
absence of finlets, and the presence of a keel on each side of the tail. When adult,
the pilot-fish measures about a foot in length. In colour it is bluish, with five or six
dark vertical bands ; the tail-fin sometimes having the ends of its two lobes dark,
as also a band across the middle third. Ranging over all temperate and tropical
seas, pilot-fish were regarded as sacred by the ancients, by whom they were known
as pompili ; the common belief being that when the ship neared land, the fish
suddenly disappeared, and thus gave warning to the sailors of impending danger.
Many legends have grown in later times as to how pilot-fish will prevent sharks



366 SPINY-PINNED GROUP.

from taking a bait by swimming round them and enticing them away ; but all
these appear to be pure fictions, and perhaps the best account of the real habits of
the fish is one by Dr. Meyen, from which the following summary is taken. It
appears that the pilot-fish constantly swims in front of the shark, sometimes
coming close to its muzzle or front fins as it approaches a ship, and sometimes
darting sideways or forwards for a short distance, and then returning to the side
of the larger ship. In one instance, where a baited hook was thrown over the
ship's side, the pilot-fish rushed up, and after swimming close to the bait, returned
to the shark, and by swimming and splashing round it appeared to be attracting
its attention. Soon after the shark began to move, with the pilot-fish in front, and
was almost immediately hooked. Instead of the pilot-fish taking care of the shark
it would rather seem to frequent the company of the latter for the sake of the
fragments of food and other substances to be found in its neighbourhood ; and it is
doubtless for the same reason that these fishes follow ships. In summer, pilot-fish
will not unfrequently accompany vessels into the southern British harbours ; but
their purely pelagic habits are indicated by the circumstance that their spawn
and fry are found far out in the open sea. The young both of this fish and of
some of the allied forms are so different in appearance from their parents that
they have been described under distinct generic names.

Both the preceding genera belong to a group of the family in
which the spines of the anal fin are detached from its soft portion.
As an example of a second group in which these two portions are connected by
membrane, we may notice the so-called sea-bats (Platax), remarkable for the great
height and compression of the rhomboidal body, and the strong development of the
dorsal and anal fins, which are often nearly similar in form and size. Indeed,
except that they are symmetrical and have an eye on each side of the head, the
sea-bats look almost like flat-fishes. They have the spinous portion of the single
dorsal fin almost concealed, and with from three to seven spines; the anal has
three spines; and the pelvic fins, which are sometimes greatly elongated, hav< a
single spine and five rays. The scales are rather smaller or medium ; the palate is
toothless; and the jaws have a series of outer teeth somewhat larger than the
small ones of the inner rows. These fish, of which there are but few species, appear
to be confined to the Red Sea, Indian Ocean, and the Western Pacific, where tin -y
are abundant. Some of them attain a length of about 20 inches, and the body may
be marked by a few broad vertical dark bands, the long lobes of the fins being black.
In young specimens the rays of the median fins are proportionately much longer
than in adults, thus giving the w r hole fish somewhat the appearance of a cheese-
cutter. Sea-bats are found in a fossil state not only in the middle Eocene of Monte
Bolca, but likewise in the Cretaceous rocks of England and the Lebanon, so that the
genus is an old one. In the allied genus Psettus, from the coasts of Western Africa
and the Indo-Pacific Ocean, the pectoral fins are rudimental.

THE DORIES, Family CYTTID^E.

The deep form of the compressed body, the division of the dorsal fin into two
distinct moieties, and the circumstance that the number of trunk-vertebrae exceeds



STROMATEIDS AND CORYPHALNAS. 367

ten. and that of the tail fourteen, form the leading features by which the small
family of the dories are distinguished from the other members of the group under
consideration. The body may be invested either with small scales or bony plates,
or may be devoid of both. The eyes are lateral, and the teeth conical and small.
There is no connection between the preopercular and the orbit ; the gill-opening is
wide, and the pectoral fins are thoracic in position. The John Dory (Zeus faber),
which gives the name to the family, and is said to derive its own title from a
corruption of a foreign equivalent of " gilded cock," represents a genus with few
species, characterised by a series of bony plates at the base of the dorsal and anal
fins, and another on the under surface ; the anal having four spines. The eight or
nine spines of the first dorsal fin, which is not much shorter than the second, are
produced into long slender filaments; and there are but few or no scales. The
genus ranges over the Mediterranean, the eastern coasts of the temperate zones of
the Atlantic, and the Australian and Japanese seas ; while in a fossil state it occurs
in the Miocene deposits of Sicily. An exceedingly ugly and ill-favoured creature,
with a huge protruding mouth, the common dory is olive-brown tinged with yellow
in colour, showing blue and metallic reflections in certain lights. The sides bear a
large black spot, surrounded by a white ring ; a similar mark occurring in some of
the other species. A somewhat migratory fish on the British coasts, the dory has
been long esteemed by epicures, and it is stated that its flesh is better on the second
than on the first day. Couch writes that " when the pilchards approach the shore,
the dory is often taken in considerable numbers. In the autumn of 1829 more
than sixty were hauled on shore at once in a net, some of them of large size, and
yet the whole of them were sold for nine shillings. It continues common until the
end of winter, after which it is more rare but never scarce. The form of the dory
would seem to render it incapable of much activity ; and it is sometimes seen floating
along with the current rather than swimming ; yet some circumstances favour the
idea that it is able to make its way with considerable activity. It keeps pace with
shoals of pilchards, so that some are usually enclosed in the seine with them ; it
also devours the common cuttle, a creature of vigilance and celerity ; and I have
seen a cuttle of a few inches long taken from the stomach of a dory that measured
only 4 inches." In the allied genus Cyttus, represented by three species, from
Madeira, South Australia, and New Zealand, the body is covered with minute scales,
there are no bony plates, the number of spines in the anal fin is two, and the pelvic
fins comprise one spine and six or eight rays.

STROMATEIDS AND CORYPILENAS, Families STROMATEIDS and CORYPH^NIDM.

These two families are collectively distinguished from the preceding by the
absence of any distinct spinous portion to the dorsal fin ; the compressed body
being either oblong, or very deep ; and there being more than ten vertebrae in the
trunk, and more than fourteen in the tail. In the first of the two the dentition
is feeble, the palate being devoid of teeth ; but there are horny barbed processes
projecting into the oesophagus which take the place of oral teeth. The scales are
very small, the eyes lateral, and the dorsal fin long. The typical genus Stromateus,
which includes about half a score species from most tropical and temperate seas, is




368 SPINY-FINN ED GROUP,

characterised by the absence of pelvic tins in the adult; the dorsal and anal iins
being long, with their points curving backwards in several of the species, and
the caudal deeply forked. In habits these fishes are partly pelagic.

The second of the two families is represented typically by the
well-known pelagic coryphsenas (Coryphcvna), popularly miscalled
dolphins. As a family, the Coryphcenidce are readily distinguished from the
Stromateidce by the absence of tooth-like processes in the oesophagus. In the
typical genus the body is somewhat elongated and compressed, the adults having
an elevated crest on the top of the head; and the cleft of the mouth is wide.
The single dorsal fin extends in a nearly straight line from the back of the head
almost to the deeply-forked caudal ; the anal resembles the dorsal in having no
distinct spinous portion ; and the well-developed pelvic fins are thoracic in position,
and can be received in a groove in the abdomen. Teeth are present in the jaws,

as well as on the
vomer, palatines, and
tongue ; the cycloid
scales are small; and
there is no air-
bladder. The cory-
phaenas, of which

there are some half -
dozen species, are

purely pelagic fishes, ranging over all temperate and tropical seas, and remarkable
for the beauty of their fleeting colours. Dr. Giinther observes that so " far as the
colours are capable of description, those of the common species (C. hippurus), which
is often seen in the Mediterranean, are silvery blue above, with markings of a
deeper azure, and reflections of pure gold, the lower-parts being lemon- yellow,
marked with pale blue. The pectoral fins are partly lead colour, partly yellow ;
the anal is yellow, the iris of the eye golden. These iridescent colours change
rapidly whilst the fish is dying, as in the mackerel. The form of the body, and
especially of the head, changes considerably with age. Very young specimen.-
from 1 to 6 -inches in length, are abundant in the open sea, and frequently
obtained in the tow-net. Their body is cylindrical, their head as broad as higl
and the eye relatively very large, much longer than the snout. As the fish gro>
the body is more compressed, and finally a high crest is developed on the
and the anterior part of the dorsal fin attains a height equal to that of the body.
This species ranges over all tropical seas, and attains a length of from 5 to 6 feet
although its flesh is unpalatable to Europeans, it is eaten by the natives
Madras. Powerful swimmers, and associating in large shoals, coryphaenas ai
determined enemies to flying-fish, pursuing them as they skim from wave to wa\
and capturing them as they again fall into the water.

sun Fish ^ an exam pl e f genera in which the body is much compi

short, and deep, we may select the sun-fish (Lampris luna), of the
North Atlantic and Mediterranean, tin- sole representative of its genus. Tin-
body is covered with very small deciduous scales, the mouth has a narrow cleft.
and is devoid of teeth, the dorsal has its anterior portion elevated into a narrow



NOMsEIDS AND MACKERELS 369

point, and the pelvic fins are composed of numerous rays. This fish, which attains
to the length of 4 feet, is remarkable for the beauty of its coloration, the body
being bluish, with round silvery spots, and the fins brilliant scarlet. Its flesh is
reported to be of good flavour. In the allied Meiie, also represented by a single
species (J/. maculata), inhabiting the Indian and Malayan seas, and attaining a
length of 8 or 9 inches, the jaws are toothed, the mouth is very protractile, and
the first rays of the pelvic fins are greatly elongated. This genus is found in a
fossil state in the middle Eocene of Monte Bolca ; while in the London Clay we
have the extinct Goniognathus.



NOIVLEIDS AND MACKERELS, Families NOM^ID^! and

Both these families agree in having two dorsal fins, and in the number of
.trunk- vertebras exceeding ten, and the caudal fourteen. In the first small and
comparatively unimportant group there may be finlets behind the dorsal and anal
tins; the dorsal has a distinct spinous portion, the caudal is forked, and the body
covered with cycloid scales of moderate size. All these fishes are marine, and, in
the young state at least, pelagic. Of the better-known genera, Gastrockisma, with
a broad cleft to the mouth, finlets on the back and abdomen, and enormous pelvic
tins, capable of being folded into a cleft in the body, and of which the position is
[thoracic, is known by a single New Zealand species (G. melampus). On the other
hand, Nomceus, with two species from the Tropical Atlantic and Indian Ocean,
3ks finlets, and has a narrow mouth-cleft.

The second of the two families is typically represented by the
true mackerels (Scomber), and is characterised by the oblong or
slightly elongated form of the body which is but very slightly compressed, and
)vered either with very minute scales, or naked and the structure of the dorsal
is. The first of these may be either modified into free spines, or an adhesive disc,
the posterior dorsal, together with the anal, is split up into finlets. There may or
ly not be an air-bladder. Characterised by their beautiful protective coloration,
lich is some shade of bluish green, mottled or barred with black above, and
lescent silver beneath, the members of this family are all pelagic and
irnivorous fish, associating in shoals, which may be of immense size, and
(frequenting all tropical and temperate seas. To enable them to keep up their
constant rapid movements, their muscles, which are consequently red in colour,
receive a much more abundant supply of blood than is the case with other
lembers of the class, and their temperature is thereby raised several degrees
ligher. Although spawning in the open sea, at certain times of the year they make
iriodical migrations towards the shore in pursuit of the shoals of herrings and
their fry on which they so largely subsist. In time, the family dates from the
lower Eocene deposits of Switzerland, where it is represented by several extinct
genera, and likewise by a species of sucking-fish; while many of the other existing
Ijgenera occur in the latter deposits.

The true mackerels are characterised by the first dorsal fin being continuous,
[with feeble spines; the presence of five or six finlets behind the dorsal and anal;
the very small scales, which are evenly distributed over the body ; the small size of
VOL. v. 24



SPINY-FINNED GR O UP.



the teeth; and the two short ridges on each side of the caudal fin. Although
there are but very few species of mackerel, these have a very wide range ; and the
genus is represented throughout the temperate and tropical seas, with the exception
of the Atlantic seaboard of Temperate South America. The general coloration
and form of mackerels are too well known to call for description, and it will
suffice to mention that of the three European forms the common mackeivl
(S. vernalis) 1 has no air-bladder, while the southern mackerel (S. pneuniatophorusl
takes its name from the presence of that organ, which likewise exists in the
Spanish mackerel (S. colias), In a fossil condition this genus occurs in the
European Eocene and Miocene deposits. Of the common mackerel, which is
represented in the upper figure of the illustration on p. 364, Yarrell writes that




NEW ZEALAND GASTROCHISMA.

"the ordinary length varies from 14 to 16 inches, and their weight is about 2 11
each ; but they are said to attain the length of 20 inches, with a proportionat
increase in weight. The largest fish are not, however, considered the best fc
table. As an article of food, they are in great request ; and those taken in tl
months of May and June are generally considered to be superior in flavour
those taken either earlier in the spring or in autumn. To be eaten in perfectioi
this fish should be very fresh." The enormous takes of mackerel which occasional!]
reward the labours of British fishermen are too well known to need mention.

Under this general title may be included not only the fish to
which the name tunny (Thynnus mediterraneus) properly pertains,
but likewise those commonly designated bonitos and albicores. The genus, which
comprises some of the largest of all pelagic fishes, differs from the true mackerels
by the greater number (six to nine) of finlets, by the scales forming a kind of

1 The author can neither admit the cnuiliinatum ,s'n*///fov ,xrWv as the title of this lish, nor that of
tli H nuns for the tunny.



Tunnies.



SUCKING-FISHES. 371

corselet on the anterior part of the body only, and the presence of only a single
longitudinal ridge 011 each side of the tail. The tunnies have a geographical
distribution coextensive with that of the family ; and in a fossil state are found
in the Eocene and Miocene deposits of the Continent. The common species, which
attains a length of over 10 feet, and a weight of half a ton, is an occasional visitor
to the British coasts, and is abundant in the Mediterranean, where it has been
regularly fished for since very early times. At the present day specimens of a
hundredweight each may often be seen in the Lisbon market ; their flesh, which
is as red as beef, being cut up and sold by weight. The bonito (T. pelamys) is a
smaller and more slender fish, rarely exceeding a yard in length, and frequenting
all temperate and tropical seas ; while the name of albicore is applied to species
like T. albicora of the Atlantic, characterised by the great length of their pectoral
fins, some of these fish attaining a length of 6 feet. Albicore and bonito will
follow in the wake of sailing-ships for weeks together. They prey largely on
flying-fish ; and Bennett writes of one species that it was interesting " to mark
the precision with which it swam beneath the aeronaut, keeping him steadily in
view, and preparing to seize him at the moment of his descent. But this the flying-
fish would often elude by instantaneously renewing his leap, and not unfrequently
escape by extreme agility." Moseley writes that, when at St. Vincent, he saw a
tunny of some 25 Ibs. in weight attracted by baits thrown into the water by some
negroes, who kept on casting in fresh ones for some time, in order to give their
victim confidence. " A very strong piece of cord, with a hook like a salmon-gaff
made fast to it, was then baited with a small fish, just enough to cover the point
of the hook, and a stout bamboo used as a rod. The cord was hitched tight round
one end of it, with about a foot of it left dangling with the hook. One negro held
the rod, and another the cord, the bait being held just touching the surface of the
water. The fish swam up directly, and took it; the negro holding the bamboo
struck sharply, and drove the big hook right through the fish's upper jaw, and
both men caught hold of the line and pulled the fish straight out on to the rock."
This instance indicates the remarkable boldness and voracity of the tunnies, the
fish in question not being six feet distant from the negro holding the pole when
it took the bait. Passing over several allied genera, such as Pelamys and Cybium,
we proceed to a more interesting group of the family.

The remarkable adhesive disc on the upper surface of the head
' at once serves to distinguish the sucking-fishes, not only from their
immediate relatives, but likewise from all other members of the class ; and it may
be mentioned that the development of this disc by means of what is called natural
selection presents one of the strongest objections to the acceptance of that
doctrine, since in its incipient stages such a structure would be utterly useless.
The genus Echeneis, to which all the half-score species of sucking-fish pertain,
differs from all those noticed above in the absence of finlets ; the sucking-disc
being formed by a modification of the spines of the dorsal, and being composed
of a number of transverse plates, varying from twelve to twenty-seven, according
to the species. It is not a little remarkable that there exists in the Indian Seas,
as also in the Tropical Atlantic, a fish (Elacate nigra) closely allied to the sucking-
fishes, but with the disc represented by a few short and separated spines ; and it



372



SPINY-FINNED GROUP



may be considered certain that this fish is the survivor of the ancestral type from
which its more specialised relatives have been evolved. The body of the sucking-
fishes is elongate and pyrit'orm ; the eyes are lateral, or directed downwards and
outwards; and the cleft of the mouth is deep. Villifonn teeth are present, not
only in the jaws and on the bones of the palate, but generally also on the tongue ;
the scales are minute; and there is no air-bladder. The second dorsal and anal
fins are elongated, and the pelvics thoracic in position. Both in this genus and
Elacate the shape of the caudal fin is subject to considerable change with age ; the
middle portion in the young being produced into a long filament, which gradually
shortens until a rounded margin is produced. At the time of the full development
of the fish the corners of the tail have, however, grown out, so as to convert the





rounded fin into an emarginate or forked one. Of the two most common members
of the genus, Echeneis remora, which is the one represented in our illustration, is
comparatively small, growing only to a length of about 8 inches ; whereas E.
naucrates, characterised by the slenderness of its form, may reach a yard in length.
Sucking-fishes are inhabitants of nearly all seas, and in a fossil state are found in
the lower Eocene deposits of Switzerland.

Sucking-fishes are commonly found attached to the bodies of sharks, although
they may affix themselves either to turtles or ships; and as they are carried l>y
their involuntary hosts through a much greater extent of water than their limited



Online LibraryRichard LydekkerThe new natural history (Volume 5) → online text (page 39 of 62)