One of the most unique and interesting branches of the animal kingdom is that division called by scientists Echinodermata, comprising animals familiarly known as starfishes, sea urchins, sand dollars and sea cucumbers. So far as is known no member of this group of animals has ever ventured on land or into fresh water. All are inhabitants of the ocean and are found from the tide-washed shore to the abysses of the sea.

The present article deals with the true starfishes (Asteroidea) and a good idea of the general structure may be gained by a careful examination of a specimen of the common five-finger (Asterias vulgaris) so common on the New England coast. It is made up of a central disk or body, from which extend five rays or arms, whence the name starfish. The animal is protected by a hard framework or skeleton, composed of many limestone plates, attached by a tough membrane and covered with a skin. Between these plates there are many small openings through which the water enters the body cavity. The plates are armed with numerous spines, attached by a ball and socket joint. Some of these spines bear little pincer-like organs called pedicellariÆ, which are capable of considerable movement. Many of these little organs are arranged in groups about the spines, which swell at the point of attachment to the surface of the starfish, thus forming a shelf or base, around which these organs arrange themselves in the form of a wreath, the spine projecting high above the center. The exact function of these little organs is not known, although they have been seen to catch small animals, such as crustacea, and this is probably one of their duties.

The lower or actinal surface of each arm is deeply channeled and perforated by many holes or pores, through which the little ambulacra or water-feet are thrust. These serve as organs of locomotion, of respiration and of perception. These water-feet form a part of the wonderful water-vascular system, which consists of a madreporic body, or sieve-like organ, opening on the dorsal or actinal surface and situated between two rays. It opens into a tube called the stone canal, which enters a circular vessel called the circum oral water tube, surrounding the mouth, and a long radial canal, to which the water-feet are attached, opens from this tube and extends along the inner surface of each ray. The water enters the madreporic body, circulates through the stone canal, the circular and radial tubes, and finds its exit through the ambulacra. The water system is directed and controlled by a set of nerves, extending from a ring of nerve matter surrounding the mouth.

The true vascular or blood system consists of a heart or hÆmal canal, which runs parallel with the stone canal from the madreporic body to the oral water tube. A set of circular and radial vessels supplies every part of the animal with the vital fluid.

The digestive system is simple and consists of a mouth, a stomach, which is large and sends a lobe into the base of each arm, and an intestine of greater or lesser length, ending in a small anal opening on the dorsal surface. The coeca or liver consists of two long, tree-like masses, nearly filling each ray and connecting with the stomach by a short duct.

Starfishes are very destructive to the oyster beds along the Atlantic coast of the United States, thousands of bushels of oysters being destroyed in a few days by them. The little starfishes attack the young oysters and as the former increase in size they move about in vast numbers, resembling in this respect the grasshoppers and locusts of the west and being fully as destructive. In a paper in a Bulletin of the United States Fish Commission, by Henry C. Rowe, it is stated that in 1882 $90,000 worth of oysters were destroyed in six months and $9,000 were spent in the same period in catching the starfishes. The method of catching these animals is interesting. Devices called “tangles” and “mops” are used. These consist of a heavy iron frame, to which about twenty small ropes, ending in a large bunch of cotton waste, are fastened. These “mops” are drawn over the oyster beds and the starfishes become entangled in the waste and are then drawn on board the vessel. As many as 1,500 starfish have been taken from a single “mop.”

The following account, published in the Evening Register, of New Haven, Conn., April 3, 1884, will serve as an example of the destructive habits of these animals: “It was reported yesterday that between November 1, 1883, and the close of navigation in December, there were caught on oyster beds adjoining the Bridgeport public beds about 15,000 bushels of starfish. Since October 1 they have destroyed over 900 acres. From six to ten steamers have been catching starfish during the past six months, at an expense of $5,000.”

When oystermen first knew of the destruction caused by the starfishes, they spent much time and labor in collecting the injurious animals, cutting off an arm or two and then throwing the mutilated body and dismembered arms back into the water, not knowing that the arms would grow out again. The animals are now collected and used as a fertilizer. The interesting power of reproducing lost arms is well illustrated on the plate, the individual figured having one perfect arm and four new ones just starting to grow.

The method of eating among some of the common starfishes is curious. When the shell of an oyster is too large to be swallowed, the starfish actually projects its stomach from its mouth, surrounds the shell with this everted organ, and digests its prey in this position. The sight presented in an aquarium by a number of these animals in this attitude is truly wonderful and odd. Another interesting performance of a member of this group is that of righting itself when placed on its back. This is performed in the following manner: One or more of the rays is twisted about until the sucking feet get a firm hold on the ground or the object upon which it is resting; this is followed by a succession of similar movements farther back in the row of ambulacra, so that the whole ray is finally twisted around and lies flat on the ground. The other arms then turn in a similar manner and the starfish is soon “right side up.”

Though hidden away in dark corners of the sea, the starfish is able to see, being quite well supplied with visual organs. The end of each ray is slightly turned up and at its summit is situated a little red eye. A long nerve extends from this eye-spot to the ring of nerve matter which surrounds the mouth.

The Atlantic and Pacific coasts abound in several species of interesting starfishes, several of which are illustrated on the plate. The most numerous of these is the common five-finger (Asterias forbesii), found abundantly on the shores of the New England states. This animal loves to hide among the rocks and seaweed, and a search at low tide will always reveal a host of them. Along the sandy shores of Narragansett Bay they may be collected at low water among the seaweed, where they feed upon bivalve mollusks, such as cockles, arks and clams.

One of the largest and handsomest of the starfishes is the Giant Mountain Starfish (Oreaster reticulatus), so common in the waters of the Bahama Islands. This species attains a diameter of fifteen or sixteen inches and is very high in the center. Its upper surface is reticulated by the crossing of the hard parts of the skeleton, and beautiful ornaments may be made by removing the softer parts and leaving only the skeleton, which forms a peculiarly latticed framework. This species is found on both sides of the Atlantic ocean; it is a common starfish in the West Indies, inhabits the coast of the United States from Florida to South Carolina and is abundant on the shores of the Cape Verde Islands.

The most common starfish of the Pacific coast is the Ochre-colored Starfish (Asterias ochracea), which ranges from Sitka, Alaska, to San Diego, California, the last mentioned locality being one of the best. It is a large species, frequently attaining a diameter from tip to tip of the arms of sixteen inches. When alive it is of a rich ochre color or brown, and the surface is beautifully reticulated by numerous club-shaped spines arranged in rows. This species is as much an enemy to the oysters of the Pacific coast as is the common five-finger to those of the Atlantic coast.

Another common starfish of the coast of California is the Vermilion Starfish, which may be collected by thousands at San Diego and Monterey. The body is very broad and the rays short and wide. It is in shape quite suggestive of the foot of a pelican or duck. The upper surface is beset with small, heavy spines, which are arranged in little festoons on the five rays. Its name is very appropriate, for it is of a rich vermilion color, varying from this to rose, yellowish or purple.

A starfish of peculiar design and startling aspect is the Armed Starfish (Nidorella armata), which is an inhabitant of the warm waters of the Isthmus of Panama. It is like a star in form, the rays being short and wide. The edge is bordered by large, squarish plates and the upper surface is marked by many little holes, giving it the aspect of a fine sieve. But the most peculiar ornamentation and the character from which the species derives its name is the row of long, cornucopia-shaped spines which extend along the center of each ray from the tip to the center of each disk. Besides this regular row of spines there are several projecting from the surface of the starfish between the rays. Taken as a whole, the dorsal surface is not unlike a miniature African shield.

During the past twenty years many interesting and curious forms of starfishes have been dredged by the United States Fish Commission Steamer Albatross, in deep water, off the eastern coast of America. Some of the species were the common forms found along the shore, such as the common five-finger (Asterias vulgaris), which ranges from low water to two hundred eight fathoms. But the majority were species new to science, which were brought up from a maximum depth of two thousand three hundred sixty-nine fathoms, a depth of about three miles.

One can hardly realize the difficulties attending the gathering of these animals from such a depth. Let us imagine that a dredge is dropped from the top of the Masonic Temple, in Chicago, a height of about two hundred and seventy feet, and drawn along the street to catch such insects, mollusks and other life as might be there. It is manifest that only a small percentage of the fauna would be represented by such a method. The depth mentioned is only forty-five fathoms, and if there is difficulty in securing a representative collection for this moderate distance, what must be the almost insurmountable obstacles when that distance is multiplied fifty times. With all these difficulties, however, the animals of the abysses of the ocean are being collected and classified.

Frank Collins Baker.