Alexander Agassiz.

A contribution to American thalassography. Three cruises of the United States Coast and geodetic survey steameer Blake, in the gulf of Mexico, in the Caribbean sea, and along the Atlantic coast of the United States, from 1877 to 1880 (Volume 2) online

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Online LibraryAlexander AgassizA contribution to American thalassography. Three cruises of the United States Coast and geodetic survey steameer Blake, in the gulf of Mexico, in the Caribbean sea, and along the Atlantic coast of the United States, from 1877 to 1880 (Volume 2) → online text (page 3 of 16)
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being kept efficient perhaps by the enormous pressure under

which they live. The abso-
lute calm of the abyssal re-
gions may be the cause of the
extraordinary development of
some of the tactile or other

Fig. 196. Cyclothone lusca. t- (U. S. F. C.) .

organs 01 sense occurring in

different parts of the skin, usually on the head or upon the
lateral lines ; some of these may be, as has been suggested by
Leydig, accessory eyes, or phosphorescent organs. The acces-
sory eyes may perform the part of bull's-eyes, thus constituting,
according to Dr. Giinther, " a very deadly trap for prey, one
moment shining that it might attract the curiosity of some sim-
ple fish ; then extinguished, the simple fish would fall an easy
prey." Some of the long filamentous organs are phosphores-
cent, while others are merely tactile.




CHARACTERISTIC DEEP-SEA TYPES. FISHES. 23

Many surface fishes also descend to considerable depths. In
fact, the migration of our coast fishes is one of the most impor-
tant problems which the fisherman has to solve, and one of
which we as yet know but little. There seems to be no seri-
ous obstacle to extensive bathymetric movements' on the part of
fishes. The silver hake, which is abundant all summer long at
the surface on the New England coast, has been taken from
487 fathoms, and appears to live in September and October at
considerable depths off Southern New England. There is reason
to believe that the mackerel, menhaden, and the bluefish also go
down below the hundred-fathom line in winter.

The fishes of the abyssal realm are very distinct from those
of the surface faunae. It is safe to say that there are more
genera common to the seas of Australia and North America than
to the littoral and abyssal faunae off the Atlantic coast of the
United States, excluding the pelagic types,- many of which
are cosmopolitan. Indeed, of the sixty or more genera which
have been dredged below 1,000 fathoms in any sea, only one
has been found in less than 200 fathoms on our own coast, and
four within the two hundred-fathom line in any sea, even in
polar regions. Of the same assemblage, only seven occur any-
where in less than 300 fathoms, and down to 500 fourteen are
added to the list. These fourteen genera represent ten fami-
lies. Out of the thirty-four family groups which are repre-
sented below 1,000 fathoms, or in mid-ocean beyond soundings,
only five are represented in any in-shore fauna, even in circum-
polar regions.

We have now considered the composition of the abyssal
fauna, as found at the greatest depths. A glance at its upper
limits may also prove instructive ; we find below the hundred-
fathom line, and within the limit of 500 fathoms, a very hete-
rogeneous assemblage. Well-known surface species inhabit
at times water of considerable depths. The cod goes below
100 fathoms ; the halibut and the Newfoundland turbot go be-
low 300, and the haddock apparently to 500, on the New Eng-
land coast. Hake are also deep-sea lovers, being recorded at a
depth of over 304 fathoms. One of the species of Phycis (P.
regius) from 233 fathoms was discovered to be electric, giving



24: THKEE CRUISES OF THE " BLAKE."

quite a strong shock to Commander Bartlett and me. The
goose-fish and the hag go down at least over 350, the " Norway
haddock " to more than 150 fathoms. The swordfish, when
attacked at the surface, is able to " sound " with ease and ra-
pidity to a depth of 500 or 1,000 feet, arriving at the bottom
with such force as to imbed its sword at full length in the mud,
and there seems to be nothing to prevent powerful swimmers
from visiting the bottom at any time when the conditions of tem-
perature will permit. Scopelus, one of the most common pelagic
fishes, may live at considerable depths : it comes up to the sur-
face mainly during calm nights.

The number of representatives of shallow - water families
dredged below 100 fathoms and down to a depth of 500 fath-
oms is quite large, but diminishes rapidly below that depth, two
or three extending only to 700 fathoms, and an equal number
to 1,000 and 2,000 fathoms.

To the bottom-living species which may have made their way
gradually down to deep water upon the continental slopes be-
long preeminently the flat fishes. Fourteen species have been
detected on our Atlantic coast, living beyond the hundred-fathom




Pig. 197. Monolene atrimana



line. One of them (Monolene) (Fig. 197) comes from 300 fath-
oms, and three genera occur well down toward the thousand-
fathom line. The pole flounder ranges beyond this limit, and
breeds in deep water. It has the cavernous skeleton of the deep-
sea fishes. In Bedford Basin, Nova Scotia, and in adjacent
waters, it lives at depths of about 15 to 20 fathoms, and yet indi-
viduals captured there exhibit the peculiarities of abyssal types.



CHARACTERISTIC DEEP-SEA TYPES. FISHES. 25

The flat fishes are represented by at least two genera fossil
in the schists of Glaris, believed to have been the bottom of a
deep sea, and in the clays of Sheppey are found fossil the three
genera Gadus, Merlucius, and Phycis, types which rarely go
below 1,000 fathoms. Of the eleven recognized families of
anacanthian fishes (flat fishes, cods, and the like), all save four
are known from the abyssal fauna. The brotulid forms allied
to the cods represent a dominant abyssal group.

Among them may be mentioned Barathronus (Fig. 198)




Fig. 198. liarathronus bicolor. About



(1769 fathoms), a small-eyed fish with marked colored bands upon
its flanks, and Barathrodemus (Fig. 199) (647-1395 fathoms), a




Fig. 11)1). Barathrodemus manatinus. About $.

cusk-like fish. One of the most interesting forms of the Bro-
tulidse is Aphyonus, with rudimentary eyes, one species of which,




Figf. 200. Aphyonus mollis. About |.

having no visible eyes, was obtained by the " Challenger " at
a depth of 1,400 fathoms, south of New Guinea ; another, A.
mollis (Fig. 200), by the Blake," in 955 fathoms. This fish



26 THREE CRUISES OF THE " BLAKE."

is covered by a flaccid, scaleless skin, is toothless, and has its
head covered with a system of wide muciferous canals, the der-
mal bones being almost membranaceous. It is either a very
ancient or a very degenerate type, but bears a remarkable
superficial resemblance to its ally, Lucifuga, which inhabits the
subterranean waters of caves in Cuba, and has lost the use of
its eyes.

The typical family of cods (Gadidse) is also numerously repre-
sented in the depths of the sea ; those forms which descend to
the greatest depths being usually of a more elongate form
than the brotulids, and with a small, often filamentous, first dor-
sal fin.

The Ophidiidse (Ophidium cervinum} (Fig. 201) are elongated
Gadoids.



Fig. 201. Ophidium cervinum. About %. (U. S. F. C.)

The Lycodidse are abundant in the polar waters and lesser
abysses of the North Atlantic and Pacific, and occur also where
the Atlantic abysses merge into the Antarctic.

The macruroids (Fig. 202) are characteristic abyssal forms,
and both specifically and individually are exceedingly numerous
at all depths below the hundred-fathom line. Seventy-five per
cent at least of the fishes brought up in the trawl from the
abyssal regions are members of this family. Macrurus is rare
below 1,000 fathoms, only one species, M. Bairdii, having strag-
gled below this limit. It is more abundant inside the five hun-
dred-fathom line, and Steindachneria, a macruroid with a high
differentiated first anal fin, has been obtained by the " Alba-
tross " in 68 fathoms. The species and individuals of Coryphae-
noides and Bathygadus (Fig. 203) are as numerous below 500
fathoms as those of Macrurus are above it. The cavernous struc-
ture and membranous texture of their skeletons are very marked,
and they seem, through their elongate forms, tapering tails, im-
mense heads, and strongly armed bodies, to be especially adapted




3.

cnlc.





CHARACTERISTIC DEEP-SEA TYPES. FISHES.



27



to life in the ooze and slime of the bottom. Macrurus Bairdii
and Phyds Chesteri (Fig. 204) are the two most common fishes
of the continental slope, where they occur in immense numbers,
and breed at depths varying from 140 to 500 fathoms.

The family Breginacerotidae, hitherto known only through a
single species, a native of the Indian Ocean, appears adapted to
living at considerable depths. The discovery by the " Blake "
of a species (the long-finned Breymaceros atlanticus) (Fig. 205)




Fig. 205. Bregmaceros atlanticus.



of this old-world genus in the Gulf of Mexico, at a depth of
305390 fathoms, is very interesting to ichthyologists.

Certain groups of the blennies, gobies and the like, often send
stragglers down to the lesser abyssal depths. They are forms
with more or less elongate bodies, and low, feeble vertical fins,
adapted neither to free swimming nor to the pursuit of prey at
the surface. They are, in fact, bottom feeders, somewhat slug-
gish in habit, and usually live among stones and hide in crevices ;
while, as a rule, fishes like the perch, the sea-bream, and the
mackerel, belonging to groups with compact, short bodies, pow-
erful fins, and boldly predaceous disposition, do not descend to
great depths, and do not wander far from the coast waters. The
Berycoidea, the first group of bony fishes to appear upon the
geological horizon, occurring early in the cretaceous, are repre-
sented in the deepest dredgings of the " Albatross " (2,949 fath-
oms) by a species of Plectromus. (Fig. 206.) The Norwegian
deep-sea expedition found a species of Beryx, and Beryx splen-
dens, a magnificent brilliant scarlet species, known hitherto only
from Madeira, was one of the most important captures of the
" Albatross," in 460 fathoms.



28 THREE CRUISES OF THE " BLAKE.'







Fig. 206. Plectromus snborbitalis. f (U. S. F. C.)



The snappers and groupers of the tropics surely range below
one hundred fathoms, but it seems hardly appropriate to regard
any of the true percoids, or any of their very near allies, as
really abyssal in habit.

Some of the scombroids seem to inhabit deep water, espe-
cially the Trichiuridae, the so-called cutlass-fishes, which may
be considered a deep-sea group. They are long, compressed, of
glistening silver color ; they date back to the chalk of Lewes
and Maestricht, and occur in the eocene schists of Glaris. A
number of pelagic scombroids have been taken under such
circumstances as to render it probable that they descend to
considerable depths. The lumpsuckers (Liparidse) are well rep-
resented by four genera, which have undergone extreme modifi-
cations characteristic of abyssal forms. They have soft, cavern-
ous skeletons, immensely developed mucous canals, and are soft
and flaccid in the extreme. The family of lump-fishes (Cyclop-
teridse) is represented below the hundred-fathom line off the
Atlantic coast.

The " ribbon-fishes " may be named with the abyssal groups,
although they have never been dredged at any considerable
depth, but are known solely from individuals stranded upon the
shores or found at the top of the water. The largest of the
ribbon-fishes is capable of rapid motion at the surface, and is
probably the animal which has most often been taken for the
sea-serpent. The " Bermuda sea-serpent," Regalecus Jonesii,
was seventeen feet long, and swam with great velocity through
the surf, and dashed itself upon the shore. It seems altogether



CHARACTERISTIC DEEP-SEA TYPES. FISHES. 29

reasonable to believe that these fishes live at comparatively mod-
erate depths, like the members of the family Trichiuridse.

Among the bottom-loving groups, the sculpin descends to 732
fathoms ; its representatives go back to the tertiary formations.

The scorpsenoids descend to 440 fathoms. Seorpsena occurs
in the eocene of Oran.

The blennies are still represented at a depth of 471 fathoms.

The gobies have a representative in deep water, Callionymus
(Fig. 207), a huge sea-robin-like fish. The discovery of a mem-




Fig-. 207. Callionymus Ag-assizii. About ^.

ber of this old-world family in the Gulf of Mexico, at a depth
of 340 fathoms, is one of the noteworthy features of the
" Blake " exploration.

We should also mention the tile-fish dredged off our Middle
Atlantic coast in deep water, the remarkable Lopholatilus cha-
mceleonticeps.

Chiasmodon niger (Fig. 208) is a species which has been




Fig-. 208. Chiasmodon nig-er. About . (U. & F. 0.)

often described, but its common name, " the great swallower,"
is so characteristic that we may here recall it to memory. It is
able to take in fishes fully half as large as itself. Gtinther



30 THREE CRUISES OF THE "BLAKE."

places it in 1,500 fathoms. Most of the specimens known have
been collected at the surface, and there seems to be a reasonable
probability that this genus inhabits intermediate depths, since
mid-depth fishes only have been found in its stomach.

The gurnards have also representatives in deep water, if the
remarkable new genus Hypsicometes is one of its members.
This has been obtained both by the " Blake " and by the " Al-
batross " at various depths from 68 to 324 fathoms, and four
species of the family touch the hundred - fathom line or go
below it.

The Agonidee are represented in 324 fathoms by one species
of Peristedium (Fig. 209), remarkable for its branching barbels,




Fig. 209. Peristedinm longispatha. About ^.



and three others found between 140 and 300 fathoms, all the
result of recent American explorations.

It is worthy of note, that the characteristic abyssal families
are apparently offshoots of free-swimming species of active hab-
its, which have, in the course of time, become gradually accli-
mated in the depths of the sea. Their approach to great depths
would appear to have been in vertical lines, rather than upon
the slopes of the ocean bottom.

One of the most aberrant types, Notacanthus, was obtained by
the " Challenger " from a depth of 1,875 fathoms. JV. phasga-
norus was taken from the stomach of a shark killed on the
Grand Bank of Newfoundland.

Many members of the group of Pediculati are often met with
swimming on the surface. They are species whose habits seem
to have become modified to those of deep-sea fishes, while they ap-
parently retain the characteristics of their surface allies, the most
familiar representatives of which are the goose-fish (Lophius)



CHARACTERISTIC DEEP-SEA TYPES. FISHES.



31



and its allies (Malthe and Pterophryne). Lophius piscatorius,
the common goose-fish of the North Atlantic, descends to 365




Fig. 210. Nest of Pterophryne. About \.

fathoms. Pterophryne, " the marbled angler " of the Sargasso
Sea, is specially adapted to live among the floating algae, to




Fig. 211. Antennarins.



which it clings with its pediculated fins, and in which it inter-
twines its gelatinous clusters of eggs. (Fig. 210.) Its ally,



OZ THREE CRUISES OF THE "BLAKE.

Antennarius (Fig. 211), has become adapted to life on the
bottom, and is found nearly down to the hundred-fathom line.
Chaunax pictus, a closely related genus, was taken by the
" Blake " in 288 fathoms. The Ceratiidae are the only pedicu-
lates which are exclusively and characteristically abyssal. Me-
lanocetus, a deep-sea Lophius in appearance, ranges from 360
to 1,850 fathoms ; the " Blake " took it in 992 fathoms.

The Alepocephalida3, the Halosauridse (Fig. 213), and Chau-
liontidse (Fig. 214), are families which have become perma-




Fig. 215. Ipiiops Murrayi. About \.

nent residents on the bottom. To the former belongs Alepo-
cephalus Agassizii (Fig. 212), a magnificent fish which attains
a length of at least three feet, is covered with silvery scales, and
is noted for its large eyes ; while allied to the scopelids, but
inhabitants of deep water, belong certain genera, as Ipnops (Fig.




Fig. 217. Bathypterois quadrifilis. About f .



215), Bathysaurus (Fig. 216), with its huge dorsal fin and fine
teeth set in many rows, Bathypterois (Fig. 217), and Bentho-
saurus (Fig. 218), a small-eyed fish, with large ventral.

The pectoral rays of Bathypterois are strangely modified ; the
anterior ray is independent of the others, and so articulated that



9




r

-




CHARACTERISTIC DEEP-SEA TYPES. FISHES. 33

it may be extended in front of the head and used as an organ of
exploration, so that we may imagine this fish feeling its way in
the dark, and exploring the ooze to discover buried in it the
animal upon which it feeds.

To the " pelagic Isospondyli " belong those groups which, like
the Scopelidae, are found from time to time at the surface, liv-
ing or dead, and which, there is reason to believe, inhabit the
intermediate depths of the ocean, having the power of ascend-
ing and descending developed to an extent which is not at
present understood.

Among the deep-water groups named above occur the most
abnormal specializations, such as powerful jaws, lancet-like teeth,
prolonged tactile appendages, and enlargement of the tube-bear-
ing scales. They have not the cavernous and feeble skeletons
peculiar to the deep-sea gadoids, and many other families, which
may have found their way gradually into deep water ; they are,
as a rule, compactly built, muscular, and are the most actively
predaceous of the abyssal forms.

The pelagic groups do not, as a rule, exhibit special modifica-
tions of form, but they are, with few exceptions, provided with
peculiar luminous appendages, which, like the cavernous skele-
tons and exaggerated mucous systems, have been by many wri-
ters attributed to deep-sea fishes in general.

In his " Challenger " letters, Willemoes-Suhm speaks of the
luminosity of Scopelus. (Fig. 219.) It is well known to the
fishermen of the
Mediterranean
that at the death
of the fish the
luminosity ceases.
We frequently
brought in scope-
lids in our tow-
nets, and could
observe the phos-
phorescence of the luminous spots, so arranged that it seems
as if the anterior ones were intended to explore the regions in
front of the fish, while those of the belly illuminated the water




Fig. 219. Scopelus Miilleri. 1. (U. S. F. C.)



34 THREE CRUISES OF THE " BLAKE."

beneath it. The " Bombay duck," so common at certain peri-
ods in the Indian Ocean, belongs to this group of phosphores-
cent fishes. It is probably, with Scopelus, an inhabitant of
deep water, coming to the surface only at certain times.

We may imagine some deep-sea types, when in search of their
food, illuminating the water around them to a certain extent by
their feeble phosphorescent light. Others carry beacons or spe-
cialized plates on certain parts of the head ; others are resplen-
dent with phosphorescent spots extending along the sides of the
body, or the back, or ventral surface ; while in others, again,
long tactile appendages play the part of lights sent out to illu-
minate dark corners, or the fins themselves may be intensely
luminous. Sometimes the whole body is phosphorescent, and
diffuses a subdued light, as is the case with some of the deep-
sea sharks. It is hoped that future investigations will solve for
us the question whether all these phosphorescent fishes are not
to a greater or less extent in the habit of swimming far from
the bottom.

Ipnops is evidently a dweller on the bottom. The eyes of this
fish have been carefully examined by Professor Moseley. They
were at first considered phosphorescent organs, but they show a
flattened cornea extending along the median line of the snout,
with a large retina composed of peculiar rods, which form a
complicated apparatus, destined undoubtedly to produce an
image and to receive especial luminous rays. 1

Malacosteus is the sole representative of a peculiar family, the
affinities of which have never been defined. Malacosteus niger

1 The existence of well-developed eyes cialized phosphorescent plates. In fishes

among fishes destined to live in the dark that have been blinded and retain for

abysses of the ocean seems at first con- their guidance only the general sensibility

tradictory ; but we must remember that of the integuments and of the lateral line,

these denizens of the deep are immigrants these parts soon acquire a very great de-

from the shore and from the surface. In licacy. The same is the case with tactile

some cases the eyes have not been spe- organs, and experiments show that bar-

cially modified, but in others there have bels may become organs of touch adapted

been modifications of a luminous mucous to aquatic life, sensitive to the faintest

membrane, leading on the one hand to movements or the slightest displacement,

phosphorescent organs more or less spe- with power to give the blinded fishes full

cialized, or on the other to such remark- cognizance of the state of the medium in

able structures as the eyes of Ipnops, which they live,
intermediate between true eyes and spe-



I

I




CHARACTERISTIC DEEP-SEA TYPES. FISHES. 35

(Fig. 220) has been taken at the surface (dead), and also in the
trawl at various depths from 335 to 1,000 fathoms, by the
"Blake," "Albatross," and "Talisman." It has a luminous




Fig. 220. Malacosteus niger.



body under the eyes, and is possibly a form belonging to the
intermediate depths of the ocean.

Characteristically abyssal is a familiar fish of our own coast,
Synaphobranchus pinnatus (Fig. 221), ranging from 239 to
1,200 fathoms. Next come the Nemichthyidae, popularly called
the " snipe eels," exceedingly elongate, feebly finned forms,
with the jaws prolonged and bill-like. Nemichthys scolopaceus
(Fig. 222) occurs along our coast in 306 to 1,047 fathoms.
Another typical genus living in considerable depths is Netta-
stoma, represented by Nettastoma procerum (Fig. 223), a new
species taken by the " Blake " in 178 to 955 fathoms.

Some of the deep-sea fishes must find it most difficult to sup-
ply themselves with food. Such types as the astonishing Eury-
pharynx, discovered by the " Talisman," and its American ally,
Gastrostomus Bairdii (Fig. 224), seem to meet the problem of
foraging by a policy of masterly inactivity. Water and the food
it contains pour into the mouth and the enormous cavity be-
hind it, which is formed both above and below by the lateral
folds of the head and of the anterior part of the body, consti-
tuting a huge pouch, capable of great expansion. The head
thus becomes an immense funnel, the body of the fish being its
shank. Perhaps the process of digestion is carried on in part
in this pouch.

This fish undoubtedly lives in the soft ooze of the bottom, its
head alone protruding, ready to ingulf any approaching prey.
Its fins are atrophied, and the power of locomotion of this
strange animal must be reduced to a minimum. The structure
of the lateral line as described by Ryder is unique. There



36 THREE CRUISES OF THE " BLAKE."

are groups of four and five stalked organs, more or less cup-
shaped, the surrounding skin deeply pigmented. The function
of these side organs is probably tactile, or they may serve some
special purpose at the great depth at which these fish live.
Analogous organs have been described in the head of the blind
cave fish. It may be that the side organs are phosphorescent,
like those of the scopelids. These side organs also recall the
sense organs of embryo fish. The respiratory apparatus is
unique among bony fishes. There are air-breathing slits, and
the water which enters the buccal cavity escapes by a small open-
ing in front of the rudimentary pectorals. The " Blake " took
specimens of this fish in 898 fathoms. It also occurs between
389 and 1,467 fathoms.

Of the selachians, few representatives have as yet been
brought to light by deep-sea explorers, nor is it to be expected
that such large forms should be captured by the methods
hitherto employed, although, as has been stated, a regular fish-
ery for deep-sea sharks (Centrophorus) has existed from time
immemorial off the coast of Portugal. A species of skate was
taken by the " Blake " in 233-333 fathoms. Scyllium and Spi-
nax also occur below 200 fathoms (Centroscyllium Fabricii
down to 671). Only three species of selachians at all special-
ized for deep-sea life have as yet been found, unless perhaps we
except Chlamydoselachus, the frilled shark, a representative of
the devonian selachians, which is found off Japan, where it pro-
bably is an inhabitant of deep water. This is one of those in-
teresting persistent types, like the Australian Ceratodus and the
American ganoids : the gar-pike and mud-fish. The Japanese
shark has the teeth of an ancient devonian type, and the em-
bryonic characters of the lowest orders of recent sharks.


1 3 5 6 7 8 9 10 11 12 13 14 15 16

Online LibraryAlexander AgassizA contribution to American thalassography. Three cruises of the United States Coast and geodetic survey steameer Blake, in the gulf of Mexico, in the Caribbean sea, and along the Atlantic coast of the United States, from 1877 to 1880 (Volume 2) → online text (page 3 of 16)