beneath the abdomen (Wass, 1955). Hopkins 

 (1947) discussed infestations of the parasitic ne- 

 mertean C arcinonemertes carcinophiJa on female 

 blue crabs showing that only light -colored worms 

 are found in the gills of mature females which 

 have never spawned. Large red worms are found 

 only on the gills of mature female crabs which 

 have spawned at least once, or in the gills and egg 

 masses of ovigerous females. Presence of large 

 red nemerteans in the gills is a sure sign that the 

 crab has spawned some time in the past. Pearse 

 (1932b) reported trematode metacercariae on the 

 gills. 



Pigment in the melanophores of C. sajndus dis- 

 plays an endogenous rhythm with a frequency of 

 24 hours in the Gulf of Mexico where there is one 

 high and one low tide per day (Fingerman, 1955). 

 The pigment is in a dispersed state during the 

 day and in a contracted state at night. This cycle 

 is maintained under constant laboratory condi- 

 tions. Superimposed on the diurnal rhythm is a 

 tidal rhythm with a frequency of 12.4 hours. This 

 rhythm is manifested by a supplementary disper- 

 sion of melanin which occurs about 50 minutes 

 later each day and is most evident when the low 

 or high tide is either in the morning or late after- 

 noon. Under constant conditions, the phases bear 

 a definite relationship to times of low and high 

 tides in the native habitat. Also, there is evidence 

 for a semilunar rhythm. Only once every 14.8 

 days are the diurnal and tidal rhythms in the 

 same phases relative to each other. 



Callinectes ornatus Ordway 



Figure 152 



CalUnectea ornatus Ordway, 1863, p. 571.— Hay and Shore, 

 1918, p. 433, pi. 34, fig. 2. — Rathbun, 1930a, p. 114, pi. 50 

 (rev.). 



Recognition characters. — Carapace, including 

 lateral spines, slightly more than twice as wide as 

 long, somewhat tumid, finely granulate through- 

 out, transverse lines distinct, metagastric area less 

 than half as long as its anterior width. Six fron- 

 tal teeth including inner orbitals, submedial teeth 

 short, variable in length. Anterolateral teeth shal- 

 low and broad, tips of first five or six acute, others 

 acuminate; lateral spines curved forward, 

 scarcely as long as space occupied by three preced- 

 ing teeth; inner suborbital angle prominent. 



Chelipeds shaped as in C. sa/>i<l>is. hut smaller, 

 with spines possibly more acute; ridges of hand 



Figure 152. — Callinectes ornatus Ordway. Animal in 

 dorsal view, legs not shown, 10 mm. indicated. 



more developed, and teeth on fingers relatively 

 larger and sharper. Abdomen of male with first 

 segment produced laterally into an acute, up- 

 turned spine. 



Measurements— Carapace : male, length, 33 

 mm.; width, 74 mm. 



Color. — Adult male: Carapace green dorsally, 

 irregular areas of iridescence at bases of, and be- 

 tween, anterolateral teeth, and on posterior and 

 posterolateral borders. Chelipeds and portions of 

 legs similar in color or more tannish green dor- 

 sally, with iridescent areas on outer and upper 

 edges of carpus and hands; chelae white on outer 

 face, blue to fuchsia on inner surface, with fuchsia 

 on tips of fingers and teeth of opposed edges. 

 Lateral spines and some anterolateral teeth, a,s 

 well as spines on chelipeds, white tipped. Walk- 

 ing legs grading from fuchsia distally through 

 violet blue to light blue mottled with white prox- 

 imally, pubescence on legs beige. Swimming legs 

 variably mottled with white; all legs with stellate 

 fuchsia markings at articulations. Under parts 

 white and blue. 



Ovigerous female : similar to male except with 

 more violet blue on inner surface of chelae; fin- 

 gers either with white teeth or fuchsia-colored 

 teeth. Legs with dactyls reddish orange grading 

 abruptly to blue on propodi, pubescence brown 

 to beige. Abdomen with iridescent areas. 



Habitat. — This crab, like its near relative, C. 

 sapidus, is a coastal species often found in estu- 

 aries, sometimes in fresh water. Brues (1927) 

 observed a large, active male that had been 

 trapped at the head of a Cuban tidal river in 

 fresh water during a dry period of about 3 

 months' duration. Lunz (1958), writing of a 

 form from the South Carolina crab fishery, 



172 



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