N. virens. This species is found from New York northward in muddy and shelly sand, and under rocks between tide-marks, living in burrows, which it lines with a mucous secretion. It is very active, and voracious, feeding on other worms, Crustacea, etc., which it captures with its horny, protruded jaw. At night it leaves its burrow and swims freely about like an eel, frequently falling a prey to fishes. In color it is dull bluish-green, with some iridescence. The gills, which are leaf-like appendages on the parapodia, are green on the anterior end of the body and become bright red farther back. This species, and N. branti of Alaska, are the giants of polychæte worms, often measuring eighteen inches or more in length.
N. pelagica. Found in abundance on the New England shore and northern coasts under stones and on shelly bottoms. The female is four to five inches long, while the male is only two inches in length. In this species the body is widest in the middle, while in other species it is widest at the anterior end. The palps are long, and the second head-piece (peristomium) is twice as long as the next segment. The color is reddish-brown and iridescent.
N. limbata. Five to six inches long; jaws light yellow, sharp, and slender; parapodia and bristles smaller on the anterior than on the posterior end; color dark brown, with light lines on the sides and appendages, pale red on the posterior end; dorsal blood-vessel apparent, and the heart-like pulsations can be distinctly seen. The male worm is red in the middle section. Found along the middle Atlantic coast on sandy shores.
Family NEPHTHYDIDÆ
In this family the worms have a long, thick, flattish body, a section of which has a quadrangular form. The lobes of the parapodia are widely separated and fringed [pg178] with membrane, appearing like double parapodia. The pharynx is very large and projected as in Nereis.
Genus Nephthys
N. ingens. Sometimes six inches long and one quarter of an inch broad; usually smaller; color whitish, with red blood-vessel showing on dorsal side; appendages dark blown; moves actively and burrows quickly into the mud; when captured often breaks off a portion of the posterior end, which it is able to reproduce; proboscis large; branchiæ between the dorsal and ventral parapodia. Found burrowing in all kinds of mud on the New England coast.
N. picta. More slender than N. ingens; color whitish, mottled with brown on the dorsal anterior end; often a dark line down the back; head square in front and triangular in the back. Found in sandy mud at low-water mark.
Family EUNICIDÆ
These are beautiful worms, having a reddish-brown iridescent body, with bright-red branching gills, which look like feathers, along the back. They form parchment-like tubes.
Genus Marphysa
M. sanguinea. Length six inches or more; color bronze or brownish-red and iridescent; has bright-red branched gills and six caudal cirri of different lengths; body flattened, except at the anterior end, where it becomes narrow and cylindrical; has powerful jaws. It is found under stones and in clefts of rocks at low-water mark, or more commonly in parchment-like tubes on shelly beaches, from Cape Cod to New Jersey.
Genus Diopatra
D. cuprea. This is one of the largest and most beautiful annelids. It is found from Cape Cod to South Carolina at low-water mark, in sandy mud-flats, living in long tubes which project above the surface two or three inches and are hung with seaweeds and bits of foreign matter. Diopatra is twelve inches or more in length and one half of an inch in breadth. In color it is reddish-brown, specked with gray, and has a brilliant whitish or opal-like iridescence. The appendages are yellowish-brown, specked with green. The body is flattened. From the fifth segment long, dull to bright red, much-branched gills, resembling plumes, [pg179] extend nearly to the end of the worm. On the ventral side of the parapodia are whitish tubercles with a dark spot in the middle. These papillæ secrete the long, broad tube in which the worm lives. The worm is difficult to capture, for when pursued it retreats quickly into its tube, which is so large that it can easily turn around within it. (Plate XLVIII.)
Genus Arabella
A. opalina. Body cylindrical, twelve to eighteen inches long, one quarter of an inch wide in the middle, and tapers to the ends, which are comparatively small; lateral appendages short; color bronze, with brilliant, opal-like iridescence; head small, conical, but blunt and without tentacles; four eyes in transverse row at the base of the head; segments well marked; coils into spirals when outside of its burrow. Found in compact sandy mud at low-water mark on the New England coast.
Genus Lumbriconereis
L. tenuis. Twelve inches or more long, and slender, like a fine cord; bright red and somewhat iridescent; very fragile. Abundant in sandy mud on the northern New England coast, and found from New Jersey northward.
Family GLYCERIDÆ
These worms are long and smooth, with numerous segments. They taper at both ends. The head is small, conical, sharply pointed, and has four very small tentacles. The proboscis, or [pg180] pharynx, when protruded, is very large and long, and appears too large for the worm. The proboscis has four hook-like jaws. These worms burrow rapidly and disappear almost instantly into the mud or sand.
Genus Glycera
G. americana. Color red or purple; has branched gills on upper side of parapodia. Found from South Carolina to Cape Cod on sandy and muddy shores and flats near low-water mark.
G. dibranchiata. Has a simple gill on both sides of the parapodia; about eight inches long and one quarter of an inch wide in the middle; proboscis one inch long and wider than the body on the upper end. Abundant from New Jersey to Cape Cod.
ORDER SEDENTARIA THE TUBICOLOUS WORMS
Many of this order construct tubes in which they live permanently. Some species of both Sedentaria and Errantia have habits pertaining to the other. These worms are without a protrusible pharynx and without jaws. The body is usually divided into two or three sections by segments and appendages of different forms. They have hair-setæ on a limited number of segments only, varying with the species; the remaining segments have uncini, or hooked comb-like rows of setæ, which are very small, but often crowded in bunches. Uncini exist also on segments having hair-setæ. Parapodia are often lacking on the posterior parts and are usually without cirri. The gills are usually confined to the anterior end and are sometimes represented by tentacles around the head. The different species have characteristic tubes, formed by mucus secreted by epidermal glands. Sometimes the mucus hardens, making a parchment-like tube; again it cements together grains of sand, or bits of shell, seaweeds, etc. Some species secrete [pg181] calcareous tubes; these are often found on rocks, in coral, and in the shells of mollusks. The anterior end of the body is more highly developed than the posterior end.
Family SPIONIDÆ
Genus Nerine
N. agilis. Two to three inches long; slender; somewhat flattened at the anterior end; head conical and sharp; the two tentacles about one half of an inch long; four eyes; color reddish-brown, light green on the sides; gills red; tentacles greenish-white. It burrows with extreme rapidity and lives on exposed beaches near low-water mark.
N. coniocephala. Two and a half inches long, one sixteenth of an inch in diameter; head conical; body flattened on the dorsal side, round on the ventral side; has two long tentacles turned backward and a membrane on the gills of the anterior segments; gills red; bristles long and numerous.
Family CIRRATULIDÆ
Worms of this family have a cylindrical body, more or less attenuated at each end; segments similar throughout; many segments with long, filamentous cirri which act as gills; and a conical head. They live in burrows.
Genus Cirratulus
C. grandis. Four to six inches long; head acute; segments numerous, short, and distinct; color dull yellow, or orange, to brown, often iridescent beneath; ventral surface somewhat flattened. Numerous long, filamentous, red to orange-colored cirri extend nearly the whole length of the body and act as gills. It is common in sand and gravel at low-water mark from Cape Cod to New Jersey. [pg182]
Family TEREBELLIDÆ
The body is cylindrical and largest on the anterior end; there are one to three pairs of more or less branched gills on the anterior end, and the ventral surface of the anterior segments is thickened by glands which secrete mucus for tube-building. These gland-spaces are called shields.
Genus Thelepsus
T. cincinnatus. Two to four inches long; pale red; marked like lacework on the back; gills have numerous unbranched filaments arising separately in two transverse rows; tubes thin, transparent, flexible, and hung with foreign substances; attached along the whole length.
Genus Amphitrite
A. ornata. Twelve to fifteen inches long; flesh-color, reddish, or brown; three pairs of red plume-like gills and numerous flesh-colored tentacles around the anterior end; tentacles constantly in motion and sometimes extended eight or ten inches; tubes a quarter of an inch or more in diameter, and firm, being composed of sand and mud. It is found under stones in mud, gravel, and sand at low-water mark from Cape Cod to New Jersey, often associated with Cirratulus grandis.
Genera Polycirrus, Chætobranchus
P. eximius, C. sanguineus. These are two species of bright-red, fragile worms, found under stones, in mud. They do not form tubes. The first is a small worm, the second twelve to fifteen inches long. Both have long, crowded tentacles extending in every direction and distended as the blood flows into them. C. sanguineus has [pg183] tentacles sixteen inches in extent, and branched gills on short pedicels on the back. They are common in mud at low-water mark from Cape Cod to New Jersey.
Family AMPHICTENIDÆ
Genus Cistenides
C. Gouldii constructs conical free tubes of grains of sand in a single layer; body short and a little curved; head obliquely flattened; two broad groups of golden bristles turned upward on each side of the anterior end; one to two inches long; color light red or flesh-color, mottled with red or blue. This is a common worm, and its horn-shaped tubes are so plentiful as to attract attention on sandy shores. They will repay examination with a glass, so beautifully are they built. The worm has bunches of golden bristles arranged in two rows close to the flattened anterior end, which make a kind of operculum to the tube. This feature makes the species easy to identify. The worm is transparent; the internal organs showing through give it the various bright colors. It is found on sandy and muddy shores from New Jersey northward.
Family MALDANIDÆ
The tubes of these animals are formed of sand, a short portion projecting, and are very abundant in certain places. There is a horny plate on the upper surface of the head, and the skin on the sides of the head is raised in folds. There is a funnel-like process at the posterior extremity; gills are lacking. Some of the segments in the middle of the body are longer than the rest.
Genus Clymenella
C. torquata. Body long, composed of twenty-two segments; the fifth segment has a collar-like fold; the caudal extremity is funnel-shaped and edged with papillæ; both [pg184] the first and the last three segments are bare, the rest have short bristles above and hooks below; head has a prominent convex plate with a raised border; worm pale red, with bright-red bands around the segments, sometimes brownish. It constructs nearly straight tubes of pure sand close to low-water mark in sheltered coves, and ranges from New Jersey northward.
Genus Maldane
M. elongata. Six to eight inches long, one eighth to one quarter of an inch in diameter; body cylindrical, cut obliquely at both ends; head bordered by a slight fold; color brown, with red blood showing through. Found in sandy mud at low-water mark, in firm, deep tubes of fine mud, on the New England coast.
Family ARENICOLIDÆ
Genus Arenicola
A. marina. Five to ten inches long; brownish-green; body cylindrical, thickest on the anterior end; anterior and posterior ends without chætæ; twelve to thirteen pairs of branched red gills on the central segments. It makes burrows eighteen to twenty-four inches deep on sandy southern shores, and can be traced by castings at the mouth of the burrow. Commonly known as "lugworm," and used by fishermen for bait.
Family SABELLIDÆ
In this family the gills arise from two semicircular bases forming the crown; the second lobe of the anterior extremity is reversed like a collar; the gill-filaments have secondary processes, and the tubes are flexible, composed of cemented mud or sand. Found under stones, the tube passing around the stone and opening upward.
Genus Sabella
S. microphthalma. Length of tube one and a quarter inches, diameter one eighth of an inch; body olive-green, specked with white; wreath of tentacles half as long as the body; tentacles pale yellowish or flesh-colored, with transverse lines of darker color. It is found on the southern New England coast.
Family SERPULIDÆ
This family forms white calcareous tubes. One of the dorsal gill-filaments is flattened, forming an operculum, or cover, with [pg185] which the tube is closed when the worm has withdrawn itself inside. The tubes are commonly found attached to shells and rocks, usually solitary, but sometimes in clusters, crossing and recrossing each other on the surface of the shell or rock. Plume-like gills are attached to the anterior end of the body. The color differs in different species. These worms may easily be mistaken for the mollusks Vermetus, which live in similar tubes of larger size, growing in masses.
Genus Serpula
S. dianthus. Tubes often three inches long and one eighth of an inch wide, the fixed end coiled and contorted, free end with circular opening; tubes often show circular ridges, marking periods of growth; operculum funnel-shaped, the exterior striated and the edge bordered with short processes; wreath of gills nearly circular and divided into two symmetrical parts; color variable. It is found in tide-pools, also on the under side of rocks at low-water mark, either solitary or congregated in masses, and ranges from Cape Cod to New Jersey.
Genus Spirorbis
S. borealis. A minute calcareous tube, in a close, flat coil attached on one side; easily mistaken for a minute gasteropod shell; worm has an operculum and wreath of gills. Found on the fronds of seaweeds, on shells, etc.
This class of animals, once placed near the holothurians, belongs with the annelid worms on account of their mode of development, their structure being entirely dissimilar. They are without segments and without parapodia. The body-cavity is filled with fluid and is traversed by connective tissue and fine muscular fibers. They are subcylindrical animals which can retract the anterior end of the body. The mouth is surrounded by tentacles, or by tentacular folds, and is at the base of the proboscis. They live in fissures of rocks, in sand, mud, rock, or coral, and in deep gasteropod shells. Their distribution is general.
Genus Sipunculus
S. nudus. The body is cylindrical, a foot or more in length when extended. It is divided into two portions. The anterior end, to the [pg186] extent of one sixth of the entire length of the worm, is capable of being withdrawn into the remainder of the body. This portion is called the introvert. The introvert is retracted by means of special muscles forming a sheath around the gullet and connected at the other end to the body-wall about half-way down the body. It is narrower than the rest of the body and is covered more or less closely with small horny papillæ which turn backward and overlap like scales. The rest of the body is divided into longitudinal furrows and circular markings, giving it the appearance of being divided into squares. These markings correspond to muscles which lie beneath. The introvert, when retracted, leaves at the opening a lobed and plaited fold of the integument, giving the appearance of tentacles. When the introvert is expanded there is a fringe-like funnel around the mouth. The body is covered with a horny cuticle and has an iridescent luster. The animal lives buried in the sand and feeds upon sand, deriving its nourishment from the organisms contained therein. The sipunculoids pass so much sand and mud through their bodies that they are said to modify the mineral substances on the bottom of the sea, as earthworms do the soil of the land.
Genus Phascolosoma
P. Gouldii. Body cylindrical, a foot or more in length, a quarter or half of an inch in diameter when expanded; but the body constantly changes in size and shape as it is contracted or expanded; surface of body parchment-like in texture and marked off in small squares; color dull white to light brown. It is found on the New England coast in sand and gravel at low-water mark.
Avicula´ria: Specifically modified zoœcia, resembling a bird's head, found only in the Cheilostomata.
Brown bodies: Brown pigment-masses contained in the zoœcia and derived from the breaking down of the polypides.
Lo´phophore: The disk bearing the mouth and circlet of ciliated tentacles.
Orifice: The open end of the zoœcium.
Ovicell: The receptacle in which the eggs develop.
Pe´ristome: The ridge around the orifice of cell.
Po´lypide: The parts of the animal within the zoœcium.
Vibra´cula: A lashing filament, or specifically modified zoœcia, found only in the Cheilostomata.
Zoa´rium: The whole colony.
Zoϫcium: The body-wall of a single individual. [pg191]
Among the numerous objects to be found on the beach at low tide are the Polyzoa, of which there are said to be seventeen hundred named species of the marine forms. These little animals, although so plentiful, are inconspicuous, and it may be said that their very existence is not known to those who are not professed naturalists; yet they are easy to see, incrusting with a delicate calcareous lacework the surface of stones and shells and seaweeds in the tide-pools, and hanging from the rocks like branches of delicate seaweeds. There is hardly a frond of even the fine red algæ on which cannot be found the little tube holding shelly saucers, or the creeping stems or branches of polyzoans. Any one of these little masses, when examined with a pocket-glass, will surprise one with its delicate and beautiful structure.
This class of animals is also called Bryozoa, and certain species have the common names of sea-mats and corallines. They are broadly divided into two groups, namely, the erect and the incrusting forms. Those having tree- or plant-like shapes resemble seaweeds, while the colonies which spread over stones, shells, and algæ resemble moss, hence the name Bryozoa (moss-animals). Both groups have the general appearance of hydroids, because, like them, they are colonies having plant forms and having their organisms inclosed in cup-like sheaths. The resemblance, however, is but a superficial one, for the Polyzoa have a much higher organization, each animal of the colony being a separate and distinct individual. They can easily be distinguished by the hair-like processes on the tentacles. The ciliated tentacles and complete alimentary system are the conspicuous differences between these colonies and those of the hydroids.
The Polyzoa are very numerous and form a most attractive [pg192] group. They are plentiful everywhere, occurring between tide-marks and at great depths on the floor of the sea. Rocks protected from the sun are often incrusted with the calcareous forms, while branching species hang from the rocks and adorn rock pools. Membranipora, in lace-like sheets, will be found on the larger seaweeds as well as on various submerged objects. The beautiful little Crisia may be looked for on the fronds of red algæ, and Alcyonidium, in soft moss-like patches, on Fucus. On some beaches are scattered the sea-mats, Flustra foliacea, looking like bits of brown paper. A pocket-lens will reveal the marvelous and orderly arrangement of the two layers of cells, or zoœcia, placed back to back. There is not a more surprising object in the animal kingdom than a living branch of Bugula. The cells on its spiral, profusely branched clusters have appendages resembling a bird's head, with its bill constantly opening and shutting. Of the erect polyzoans some are entirely calcareous and rigid; such species live in deep water, and their colonies are called corallines, as are also the calcareous algæ. They have existed in vast numbers since early geologic times, and are plentiful in the Tertiary deposits, known as Coralline Crags. Other erect forms have a calcareous framework, which is not continuous, but has horny intervals, so that the colonies are flexible and can be swayed by the tides in shallow water where they live. Others have complete horny exoskeletons. The same differences occur in the incrusting forms, those on the seaweeds being either flexible, so that they bend with the plant, or if entirely calcareous are so small that they do not break when the plant sways to and fro. Still others are gelatinous and resemble bits of sponge. The calcareous forms are usually ornamented with ridges which form beautiful patterns.
The individuals of the polyzoan colonies are small polyp-like organisms which have a cup-like inclosure of horny or of calcareous substance, or of the two combined, as mentioned above. This inclosing sheath is the exterior or cuticle of the animal and is called the zoœcium, the whole colony being called the zoarium. The animal substance within the zoœcium is the polypide, and consists of the mouth, tentacles, and alimentary system. A disk at the anterior end of the body, bearing the circle of tentacles, is [pg193] the lophophore; it is a contractile body, being, with the tentacles, protruded from the zoœcium or drawn within it at will. In some species the orifices of the zoœcia are surrounded with spines; others have lids, called opercula, which shut down when the polypides are retracted. A singular modification of the zoœcia is seen in the genus Bugula, where peculiar shapes like birds' heads, called avicularia, occur. In these singular appendages the upper beak is hooked, while the lower one, or mandible, is the operculum of the zoœcium. These constantly open and shut by means of muscles, and although their function is not certainly known, it is thought that they capture prey. Other modifications are whip-like processes, or flagellate filaments, called vibracula, which constantly beat the water. In many of the zoœcia of the colony there are dark-colored masses, called brown bodies. These are formed by the degeneration of the polypides, which at certain periods break down, their tentacles and alimentary system ceasing to act and becoming brown masses. The body-wall then puts out a bud internally and forms a new polypide, which absorbs, or passes out, the brown body. The term of life of a single polypide is not known, but in every colony many such transformations are constantly taking place.
The colonies originally start from larvæ produced in the ovicells of the zoaria. The ovicells are sometimes very large and pear-shaped, occurring at intervals on the stems; or there may be one at the top of each zoœcium. They look like pearls. A larva, when liberated, swims about for a time, then attaches itself to a fixed object, and increases, by budding, into some one of the various forms which the colonies take.
Suborder CYCLOSTOMATA ERECT OR CREEPING POLYZOA
The zoœcia are more or less cylindrical; the upper ends are sometimes completely free and sometimes closely adherent. The [pg194] opening of the cell has no operculum. Ovicells, containing the embryos, appear like pear-shaped swellings.
Genus Crisia
C. eburnea. This species is found in tide-pools on algæ, especially on the red seaweeds, growing in bushy tufts from one half of an inch to an inch high. Calcareous, with horny joints; cells in two rows, semi-alternate, cylindrical, free at one end, bent; no operculum; ivory-white; ovicells large and pear-shaped. Common from Long Island Sound northward and on the Pacific coast.
Genus Tubulipora
T. flabellaris. This species is found attached to slender branched algæ, in coral-like masses of long, crooked, tubular cells united at the base and spreading into fan-shapes placed flat against the fronds. It is sometimes one quarter of an inch in diameter. On the same alga may often be found Crisia, Mollia, and Cellepora. (Plate XLIX.)
Genus Diastopora
D. patina. Tubular cells rise from a saucer-shaped disk about a quarter of an inch in diameter; cells lie obliquely or stand erect, and are crowded toward the center; margin of disk without cells; colony white and calcareous. Found on algæ and eel-grass from Long Island Sound northward.
Suborder CHEILOSTOMATA
In this suborder the zoœcia are either horny or calcareous, and the orifices are usually surrounded with spines and have opercula. The orifices generally have raised margins, or peristomes. Ovicells form helmet-like coverings overhanging the orifices.
Genus Ætea
Æ. anguinea. Delicate, white, creeping, calcareous stems, from which rise numerous club-shaped cells, about one eighth of an inch high, each one with an aperture in the end. This species creeps in wavy lines along the fronds of algæ, and is frequently found on Dasya, Griffithsia, Plocamium, and eel-grass.
| PLATE XLIX. | ||
|---|---|---|
| Tubulipora flabellaris. 1, Tubulipora flabellaris, natural size. | Eucratea chelata. | Cellularia ternata. 1, Cellularia ternata, natural size. |
| PLATE L. | ||
|---|---|---|
| Caberea Ellisii. | Bugula turrita. | 1, Bugula Murrayana; 2, B. Murrayana, magnified; 3, B. Murrayana, a few cells, more highly magnified; 4, B. flabellata; 5, B. flabellata, magnified. |
Genus Eucratea
E. chelata. A small, delicate species rising from a creeping stem. It has branches composed of single rows of horn-shaped cells having an oblique aperture on the side. Found at extreme low-water mark on hydroids, shells, stones, and Fucus. (Plate XLIX.)
Genus Cellularia
C. ternata. Zoarium filamentous, spreading, about one inch high, white, calcareous, branched in a forking manner; cells long, narrowest at base, arranged in series of three and on the same plane, apertures oblique and facing one way; horny joint between each cluster of cells. This species grows in deep water from Cape Cod northward, and is found on objects washed upon the beach. (Plate XLIX.)
Genus Caberea
C. Ellisii. Zoarium erect, with fibrous base, leaf-like, branches in a forking manner; branches straight, stiff, narrow, spreading; cells arranged in rows of three, adherent throughout; long bristles emanate from near base of many cells; egg-capsules globular, smooth, pearly. Common from Cape Cod northward in deep water. (Plate L.)
Genus Bugula
B. turrita. This is a very abundant species, found everywhere along the coast from Maine to North Carolina. Large quantities of it are [pg196] sometimes thrown upon the beach by storms. It grows in erect tufts, sometimes a foot long, and is much branched; the branches grow around the stem in a spiral manner, forming dense clusters. The lower part of the stem is often naked (having lost the branches) and bright orange in color, while the tufts of branches at the top are pearly-white or yellowish. The cells are long, with a long, pointed spine on the upper outer angle. Like all species of Bugula, it has bird-head appendages, which can be seen under a powerful glass. (Plate L.)
B. Murrayana. Clusters of broad, thin, flexible fronds, one to two inches high, attached by a slender base and spreading in entangled masses; fronds wedge-shaped, flat, dividing in a forking manner; outer cells have bristle-like filaments, which constantly beat the water; all cells have avicularia, or bird-head appendages. (Plate L.)
B. flabellata. Fan-shaped fronds of flat branches, divided in a forking manner; the cells are arranged in four or five longitudinal rows, are oblong, with a spine at each side of the circular aperture, and are capped with pearl-like ovicells. This species, like others of the genus, bears the very singular structures known as avicularia, or bird-head appendages. They show, under a strong glass, a hooked beak, like that of the hawk or parrot. These beaks are attached by flexible stems and are provided internally with powerful muscles by which they are constantly opened and closed; the beak can bite with considerable force. In this species they are attached to the sides of the cells. (Plate L.)
Genus Flustra
F. membranacea. This species forms gauze-like incrustations on the fronds of seaweeds, and is common on Fucus and Laminaria, spreading irregularly over several inches of space. The cells are oblong, quadrangular, with a blunt, hollow spine at each angle. Many specimens have simple horny tubes, closed on top, rising from some of the cells to the height of half an inch. (Plate LI.)
| PLATE LI. | |
|---|---|
| Flustra foliacea. | 1, Flustra membranacea; 2, 3, F. membranacea, magnified. |
| 1, 2, Cellepora pumicosa, natural size; 3, C. pumicosa, magnified; 4, C. ramulosa. | Vesicularia dichotoma. |
Genus Membranipora