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Home , Anthozoa, Coelenterata, Hydra (genus), Hydrozoa, Polyp (zoology), Sea anemone

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JELLYFISHES AND RELATED by Victor L . Loosanoff Biological Laboratory Bureau of Commercial Fisheries U.S. and Wildlife S ervice Milford, Connecticut

CONTENTS

Page Page

Introduction •...... 2 ...... 6 Stinging cells or nematocysts . 2 Control of ...... 7 ...... •...... 3 ...... 8 Scy phoz oa ...... 4 References ...... •.•..... 8

INTRODUCTION vibrating cilia, and others by the con­ traction and expansion of their soft or, as they are often called, bodies. " nettles " belong to a very large and Coelenterates are aquatic animals. The complex group, or , of animals which majority of the m are marine, but several scientists call . This name is fresh- w ater fo rms are also known. Until deriv ed from the two Greek words "coel," the middle of the eighteenth century little meaning "hollow," and "ente ron," meaning exact knowledge was available regarding " gut, " and refers to the fact that the main the structure of coelenterates and their ca ity of the body of these animals is the position in the kingdom. They were digestiv e one. considered either or -animals. Coelenterates are classified among the Often they were regarded as the connecting lowest many-celled animals because they link between plants and animals. Towards are without many organs and tissues , which the end of the eighteenth century, however, characterize the higher forms. The most the a n i mal nature of coelenterates was familiar examples of Coelenterata are jelly­ definitely proven. , hydroids, sea , , and Coelenterates possess two distinctly dif­ sea fans. Some c oelenterates are stationary; ferent types of structures. T hey are (1) the of these some branch like plants, some or type and (2) the medusa move about by the aid of , some by or jellyfish type. The first type is seen in

UNITED STATES DEPARTMENT OF THE INTERIOR, Stewart L. Udall, Secretary FISH AND WILDLIFE SER VICE, Clar2nce F. Paullk2, Commissioner BUREAU OF COMMERCIAL FISHERIES, Donald L. McKernan, Director

Fishery Leaflet 535

Washington 25, D,C, February 1962 ) ) its s im p l est form in t he very common by minut quantities o f a poisono sub­ fresh - water animals called , and stanc found in th threads. Th n m ato ­ h y dropolyps, and in more compl x forms cysts of j llyfish and oth r co 1 n t r a t es in the corals. In all these animals the body s rv both as o f d efens and for is cylindrical in form , on end usually th purpo e of stunning or killing the s m all being attached to some more or less animals which form the f ood o f t h sea stationary object, while at the other end is n tIs. t he surrounded by tent acles . Th Th "sting" o f he majori y o f he second, or the medusa type , is found in co lenterat i not perc p lble to man. jellyf ishes. In this case the body IS mor This pecially ru of numbers o f o r less cup- shaped, the convex side cor­ Hydrozoa, whlch may be handl d wi h im­ responding to the attached end of the hydrold punlty, wi h h exc p lon o f h MIllepor ma , pol yp, while from the center of the concav or Siphonophora, an con aining fr e e ­ side extends the manubrium, a more or le s float ing communi le of hydroids . The cylindrical projection, at the end of which mlllepor 5, however, and some 0 he r is the mouth. Tentacles may be pr sent , as well as gorgonians (sea fans), either on the manubrium, at the edge of he produc a . mgmg n a lOn of hor dura - cup, or on the convex or concave surfac s lon. Th spong dlver of th M diter ­ of the animals. ranean are ald 0 suffer greatly f rom skm leslOn" and de p wound of the hands caus d by an hat liv s among he spong STINGING CELLS OR NE MA TOCYSTS lost , or true Jellyfishe , ar ha rmiul and hould be approached wi h The presence of jellyfishes in the wat r cautlon. C)anea, a common Jellyflsh of near bathing beaches is undeslrable be ­ Am ncan hores, may ca se dangerous cause some of them, coming m contac burn:.. The mo dangerous Scyphozoa with the human body , may stmg and irrl ate are Oactylometra and Chiropsalml.(S, inhabi an s the skin. The stingmg IS caused by hlghly of warmer waters , whose sing can ca se specialized stinging capsule s called \ery erlOUS lllness or even deah . nematocysts, of whIch there are several Probably h most dangerous coelen era e varietIes . The stingmg capsules he m IS PAy alia (Portuguese man- of- war)' a special cells located in the outer layer of hydrozoan. The mjuries from he last the jellyfish body. Very often they are three coelen era es range from a burning found arranged in large groups . A nema­ pam a he Sl e of con act to skin le ions tocyst is oval in shape . It has an outer and eruptlOns, of en severe enough t o capsule provided with a short tngger hair, leave scars, to general pain, f ever, prostra ­ or cnidocil, a t the free end, close to the tion, and resplra ory interferences . apical o pening. This o pening is closed by a The nature of the material injected fr o m special pl ug. Within the outer capsule is nematocysts 1 not known. Formerly it was an inne r capsule containing a spir aled fila ­ believed to be formic aCld, but recen ment. This f ilament is a hollo w tube, its studies on this subject do not support that wall being c ont in u ous wit h that o f the inner conclusion. capsule. When the c n idocil, o r trigger The coelenterates a re divided into three hair, comes into c ontact wit h an object, or classes: Hydrozoa (hydr alike ani mals ), when the jellyf i s h rece ives a chemical Scyphozoa (cup animals), a n d Ant hozoa stimulus , the nematocyst " e x p lode s , " i . e ., ( animal ). The f ollo wing i s a bri e f the coiled f ilament is qu ickl y d ischar ged discussion of each of t h e s e classes . t hrough t he apic al o p ening. T he end o f the f ilament , which is a rmed wit h several m inute b arbs , p e netrates t he body tou ching HYDROZOA the jellyfi s h. In a ddition to purely m e cha n ical injury Hydrozo a inc 1 u de s the fresh - wate r caused b y p e netration of the b a rbed f ila ­ h ydr as , s e aweedlike z o ophytes, many j e lly­ ment, a chemical irritation is also produc ed f i shes , m o stly of small size, and a few

2 stony corals, which in some respects are case of females, and spermatozoa, in male ) different from other stony corals. This individuals, are discharged in the surround­ contains over 3,000 . ing water. When the egg and spermatozoon ) The vast majority of Hydrozoa are meet, the egg is fertilized and begins to marine. The best known exception is develop into a hydra. Hydra which is found in fresh water and Sexual does not occur in is cosmopolitan in its distribution. A few h y droids, which are the nearest marine species of medusae also have been found relatives of fresh-water hydras. Asexual in fresh or very bracki sh waters. Para­ reproduction by is the usual method sitism, although rare, is not unknown in of increasing their numbers. In old colonies this class. For example, , one of hydroids not all members of the , of the forms of this group, is parasitic t he so-called " polyps," are alike. Some-are during part of its e xistence in the ovaries reproductive polyps and are designated for of the sturgeon living in the Volga River. a special type of asexual r eproduction. Probably the most interesting group of Each reproductive polyp is enclosed by Hydrozoa is found intheorderSiphonophora a transparent, horny, v ase- shaped covering conta inin g free-floating colonies of and consists of a stock on which are borne hydroids. The Physalia of this little saucerlike buds. The largest and order includes the f amous Portuguese man­ most completely developed buds are near of-war. This animal, or rather colony, is the top, w h i le the smallest and least de­ perhaps the best known of the group, since veloped a re found near the base. 1£ the it attracts much attention in southern colony is kept in a dish of sea water, it waters. The most prominent part of the will be easy to observe that the topmost compound body is the float, an oblong, "saucer" escapes through the opening at pear-shaped bag, full of air, which floats the upper end of the vase- shaped covering on the surface of the water. Its color is and swims about as a tiny animal, which is u sually bright blue but sometimes it has called a medusa, the name often applied differ ent shades. On the upper side of this to any free- swimming jellyfish type of a ir- vessel is a crest, or sail, and from coelenterate. the under side hang long tentacles. Some The primary function of the medusa is ) of these tentacles are covered with stinging . When the medusa has cells that can readily paralyze a large matured, the e ggs and are shed in f ish. Others have feeding and reproductive the water w he r e fertilization takes place poly ps. The tentacles can reach a remark­ (fig. 1). The fertilized egg undergoes able length--up to 100 feet. They perform gradual development into a ciliated . a number of functions, acting a.s anchors The larva swims about for a time, finally or changing the CGu r s e of the animal. settles on a rock or on a piece of kelp, Or inarily these long tentacles are more becomes fastened at one end, develops or les s curled up under the air-bag pro­ tentacles around the mouth at the other truding on the surface. The vivid blue end, and grows into a polyp which, by float is a f a m iliar and v ery beautiful sight asexual budding, produces a new colony of on the surface of warm all over the sessile hydroids. The cycle is thus world, but it is not very welcome to completed. This process is known as "al­ swimmers, who know that the trailing ternation of generations." The most familiar tentacles can inflict serious and some­ example of this type is the , a times fatal injuries. common , occurring in the form Some form s of Hydrozoa, such as the of a delicate, whitish or light brown, al- hydras, reproduce sexually at certain times - most furlike growth on seaweeds, the wooden of the year, generally in the fall or winter. piles of docks, etc. In some specie s both male and female Not all Hydrozoa are of the above type. cells occur in the same individual, which is In some forms there is no medusa stage. then known as a . In other In others there is no hydroid stage, the species the two sexes are always separate. animal always being a free-swimming When the animals are ripe the eggs, in the m edusa.

) ) 3 FREE -S WI .... ING / SEXU AL STAGE SESSILE COLONY ASEXUAL STAGE

o FERTILIZED EeO

YOUNG POLYPS CILI ATED LARVA /

Fl~ure l.- -Ufe cycle of Ob~l,a Description In teXl.

SCYPHOZOA fIshes. The body of a jellyfish consists The second class of coelenterates, mostly of water; the solid matter usually Scyphozoa, includes the large jellyfishes. does not exceed 1 percent. The life span of Scyphozoa are all marine and the majorit y jellyfishes does not exceed 1 year . Even are pelagic , i .e., they WIm freely on the the giant Cyanea , which sometimes h as surface of the o cean. A few inhabit the deep discs 12 fe et in diamete r and trailing sea and have been dredged from a depth as tentacles o ve r 100 feet long, attains its immense growth in 6 months . great as 2,000 fathoms . Nearly all are free- swimming in the adult s tage ; some, In Scyphozoa the sexes a re separate. however, live on c oral reefs or mud banks The gonads of the female produc e eggs; on the bottom of the ocean. The Scyphozoa those o f the male, sperm. These sexual class includes about 200 species . organs are usually v ery brightly colored. Jellyfishes var y in size from a fraction The eggs in the female are fertilized in of an inch to 12 feet in diameter. They the l a rge central cavity by sperm which differ in the number, size, and po sition of enter the body of the female with currents the tentacles , the positi on of the egg sacs, of water (fig. 2). The fertili z ed egg (fig. etc . ; but the general plan of the internal 2A.) begins to divide (fig. 2B . ) and de ­ structure is the same in all spec ies . Many v elops into a ciliated larva called " " j ellyfishes are semitransparent and glassy, (fig. 2e.). It i s a transparent sphere cov ered but often with brilliantly colored tentacles, with hairlike structures by means of which radial canals, and egg sacs (gonads ). They i t swims about for some time a fter leaving are all carnivorous, mostly living on small the body of the mother jellyfis h . F inally, it organisms, but are able, in the case of the attaches itself to some object and becomes larger species, to digest and a young polyp (fig. 2D.). It continues to

4 J. F REE SW IMMING MEDUSA SE XUAL STAGE A. LI ZED EGG

e 9. DI VIDING EGG /

" C. CILI ATED LAIIVA

I. IMMATURE JELLYFISH~ \ H. EPHYRA ~ i

E. YOU NG SCYI'HI STDIIA ASEXUAL STAGES

G. STRDBI L A

F. MEDIUM ADVAN CED SCY PHISTOMA

Figure 2.--Life cycle of Aurelia. Description in text. )

g r o w and a c qui re a more e l ongated form over the world. Large schools can be seen with t ent acl es, a stage known as "scyphis­ d rifting along together or swimming slowly toma " (fi g. 2E.). At certain sea.sons thes e by rhythmic contraction of their saucer­ polyps dev elop a s e rie s of h orizontal con­ shaped body (fig . 3). They range in size striction s wh ich g r adually deep en until the from l es s than 3 inches to about 12 inches poly p s b egin t o res e mble a ser i e s ' of a c ross the bell. These jellyfishes may be s a ucers p il e d one on top of the other c alled annual animals, for they make their (fig. 2F.). In the late s t ages of this d e­ a ppear a n ce regularly as free- swimming v e lopme nt polyps are calle d "strobila " m edusae in the latter part of April, when (fi g . 2G. ). Each of thes e saucers, beginning t h ey may b e seen in large numbers. At with t h e topmo st, i s fin ally detach ed and tha t t ime they are only about 1 inch in bec ome s a f r e e - s w immin g preme dusa fo r m d i a meter. However, they grow rapidly and known as " ephy ra" (fig. 2H. ). Sometime b y the end of June attain full size. At the later ephy r a d e v elops fu rther into an im ­ end of July, when they are fully developed, mature jellyfish (fig . 21. ) and e v entually they begin to discharge their eggs. After becomes a matu r e , f ree-sw imming medusa t he spawning p e r iod the jellyfishes appear ready for sexu al reproduction again. T h ere t o be exha usted and die later in the year. are some species, however, wh i ch hav e T h e g enus Cyanea is another well-known neither a h ydro i d nor strobila st ag e and group of this class. It contains the which mature wit hou t an alternat ion of l a r g est jellyfis h known. As mentioned gen erations. p reviously, some individuals measure 12 Aurelia i s one of the commone st of feet a cross the d isc and have tentacles the s cyphozoan j ellyfishes a n d occur s all a bout 100 feet long. Cyanea is usually

) 5 Figure 3.--A typical rree-!wlmm1~ medusa.

solitary, seldom being seen in company 10 0 Z, 00 fa horns . The majori y of the with others . The common name for are a tached bu are able Cyr1nl'<1 is sun jelly or sea blubber. to change thelr loca ion . Some forms Wlm The stinging capsules of .1urella do not when hey are young, bu in the adul stage readily penetrate the human skin, but they burrow in he or mud leavmg even a small Cya:nea can raise huge welts only heir entacle expo ed. The sea on the arms or legs, oLd the monster anemones reproduce from he egg and orange and blue Cyanl a of the 0 r t h pass through a lan.'al stage. A he end of Atlantic is a real danger to swimmers. the free - . wimmmg period he larvae a ach themselves to solid objects and grow in 0 adul indivlduals . Reproduc ion by budding ANTHOZOA or is also common (fig. 4) . The third class of coelenterates, the Anthozoa, contains the sea anemones, the stone or corals, and the less con­ spicuous forms, such as gorgonians or sea fans, and sea whips . In general, this class consists o f animals which have no jellyfish or medusa stage. It contains over 6,000 species . Sea anemones are probably the most common representatives of Anthozoa. They vary greatly in color and form, and when expanded resemble . They are c os­ mopolitan in their distribution, but larger and more highly colored s pecies are found in tropical waters. Many of the species are found in tidepools and on piling of wharfs and bridges at the low- water mark. Figure 4.--A typical sea anemone, MetridilJlTl dianthus , in the Others have been dredged from depths of process of fission. 6 The sea anemones are carnivorous and diameter. When irritated many of the ) very voracious. They feed on small organ­ species throw out long slender white . isms. To secure their prey they are armed threads, which are cov ered with stinging ) with an abundant supply of stinging cells cells. These organs of defense protect the located under the tentacles, and also with a n imals from attack by many enemies. stinging threads which are ejected from The stone or reef corals, the second their bodie s. well-known group of Anthozoa, resemble The genus contains the best sea anemones in their general structure, known species of sea anemones. It is c om­ but are usually colonial and secrete pro­ mon along our shores and is found near tective limestone cups into which the small the low-water mark in tidepools and in delicate animals can retreat (fig. 5). They sheltered crevices of rocks. Some of the have a wide distribution, but the number species found in Florida are 18 inches in of forms in temperate ree:ions is l'lmall.

)

Figure 5.--Stony coral. muricata, from Dry Tortugas. Florida.

The majority , including stone or reef build­ CONTROL OF JELLYFISH ing corals, are confined to tropical parts of the Atlantic, Indian, and Pacific Oceans, In the summer, jellyfish are abundant flourishing only when the lowest winter along the shores of our Middle Atlantic temperature does not drop below 680 F. States, and their presence, at times, pre­ Many of the Pacific Islands are formed vents people from swimming. Unfortunately, entirely of coral rock. The Great Barrier so f ar, no satisfactory method has been Reef of Australia, e xtending for a distance dev eloped for their control or eradication. of 1,250 miles, consists of gigantic masses The practice of fencing off swimming areas of coral rocks fringed by living corals. with small mesh wire netting was tried in Some of them are considered precious and several localities. However, since small command quite a high price. jellyfish can easily squeeze through the

7 netting, and because fragments of their Ctenophora. The name of the phylum means bodie s , brok en by contact with the wire "comb-bearers " because of the rows of netting, can also easily enter fenced off flat cilia, arranged as the teeth of a comb, areas , the meth od is often ineffective. along eight meridional lines over the sur­ Recently, e xperiments hav e been con­ face of the animal. These animals are ducted t o k eep jellyfish from entering commonly known as "sea gooseberries " or bathing areas by c r eating in the w ater a " sea walnuts." The phylum Ctenophora con­ w a ll of air bubbles rel eased from perforated sists of about 100 species, 21 of which hose s laid on the bottom. The results of occur off the Atlantic . In this group the se e ffort s h a v e not been t horoughly the stinging cells are replaced by adhesive e va luated as y et. It appears, nevertheless, cells which stick to, and entangle the prey. that during periods of relatively strong The ctenophores are transparent, gelat­ winds, or in areas where tidal currents inous creatures, which float on the surface are s t r ong , this method cannot stop jelly­ of the sea mostly near shores. Being feeble fi s h or parts of their bodies from ente r ing swimmers they are carried about by cur­ bathing beaches. rents and tides so that they often accumu­ There a re a number of chemicals which late in vast numbers in some bay s or are known to kill j ellyfi sh, but most of harbors where winds and tides hav e driven t hem, unfor tunately , may also inj ure other them. They are widely distributed and found important marine forms or may be danger­ in all seas . ous to s w immers. Some chemi cal m ethods, The ctenophores are hermaphroditic, both however, may be applicable in c ertain areas m ale and female sex cells being found in where currents are not strong and will the same individual. The egg dev elops into not, theref ore, bring new masses of jelly­ a free- swimming larva wh i ch, in turn, de­ fish into areas that hav e been r e cently velops directly into an adu lt. They subsist cleaned of t hem. For example, spre ading upon small p lants and animals found in sea finely g ranulated, hot lime (calcium ox ide) water, which enters the bodies of cteno­ on the su r face of the w ater may be effec­ phores through their circulatory systems. tive. Particles of lime falling upon surfaces It is believed that at least one genus of of the j e llyf ish b odie s will become i mbedded ctenophores, Mnemiopsis, des t roy s 1 a r g e in the t issue s and quickly disintegrate n umbers of larvae of and othe r them. At the same time, the particles are m ollusks. sufficiently h e a vy to carry the injured jellyfish t o the bottom. In recent e xper iments conducted in Long REFERENCES I s l and Sound to e xter m inate and Buchsbaum, Ralph. other e nemie s of oyste rs, b i ol ogists of the 1948. Animals w ithout backbones . The Bureau of C ommercial F isheries noticed that particles of sand coated with highly University of Chicago Press, insoluble chemicals, such as orthodichloro­ Chicago, Illinois, 405 p. benzene, also quickly killed jellyf ish and carried them to the bot tom. These e x peri­ Fraser, C. McLean. ment s a nd obs ervati ons may suggest a clue 1910 . Some h y droids of Beaufort, North f or the c ontrol of jellyfish. Perhaps spread­ Carolina. Bull e tin of the U.S. ing sand alone on the w ater surface will b e Bureau of Fisheries, vol. 30, p. sufficient to s ink jellyfi sh to the bottom, 337-387. (Document 762, issued thus clear ing the a reas of their presence. J ul y 25, 1 9 1 2 • ) T his met h od may be e s pecially suitable where c u rrents are slow and, therefore , Hardy, Alister. no new mas s es of jellyfish will quickly 1956. The open sea. Houghton Mifflin r einvade the cle a red areas. Co., Boston, 335 p.

CTENOPHORA Hargitt, Charles W. 1902. The anthozoa of the Woods Hole Anot her g r oup of anim a ls, which resem­ region. Bulletin of the U.S. Bureau ble jellyf ish e s in gener a l appearance, was of Fisheries, v ol. 32, p. 223 -254. f o r merly in cluded with c o elenterates, but (Document 788, issued April 25 , is now classified in the separate phylum 1914.)

8 Hargitt, Charles W. Miner, Roy Waldo. 1904. The Medusae of the Woods Hole 1950. Field book of seashore life. ) region. Bulletin of the U.S. Bureau G. P. Putnam's Sons, New Yo rk, of Fisheries, vol. 24, p. 21-79. 888 p. (Document 558, is sued February 14, 1905.) Nutting, Charles C. 1899. The hydroids of the Woods Hole Hyman, Libbie H. region. Bulletin of the U.S. Bureau 1940. The : Protozoa of Fisheries, vol. 19, p. 325-386. through Ctenophora. McGraw-Hill (Document 455, issued June 10,1901.) Book Co., Inc., New York, 726 p. Pratt, Henry S. MacGinitie, G. E ., and Nettie MacGinitie. 1951. A manual of the common inverte­ 1949. Natural historyofmarineanimals. brate animals exclusive of insects. McGraw-Hill Book Co., Inc., New The Blakiston Co" Philadelphia, York, 473 p . 854 p.

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