FISHERY BULLETIN: VOL. 81. NO. 2 



Table 3.— Postparturition growth [total length (TL) and total 

 weight] of two captive juvenile Odontaspis taurus from observations 

 made by F. G. Wood at Marineland Inc., St. Augustine, Fla. NR = 

 not recorded. 



'37 mo old. claspers extended 7.5 cm past pelvic fin tip. 



cm 0. taurus female was captured 10 April 1946 and 

 kept in an aquarium for 11 mo; it died on 9 March 

 1947. Her autopsy revealed two decomposing near- 

 term embryos 103-105 cm TL (6.1 and 6.4 kg) 

 (McBride 1947 10 ; Springer 1948). 



The oophagous stage in development is preceded 

 by an increase in ovary size, ovulation rate, number of 

 ova per capsule, and number of Type II capsules pro- 

 duced. The number of ova per capsule increased to a 

 maximum of 23 ova/capsule during the fall and win- 

 ter (Fig. 5D). During late gestation the embryos 

 swallowed such great quantities of yolk that their 

 stomachs became greatly distended. Cadenat (1956) 

 found 1.5 kg of yolk (18.8% total body weight) in a 

 near-term 0. taurus embryo weighing 8 kg. This dis- 

 tention of the abdomen has precipitated the term 

 "yolk stomach" used by earlier authors, particularly 

 for the oophagous embryos of Lamna nasus ("Dot- 

 termagen" of Lohberger 1910). 



The distention of the embryonic stomach declines 

 in the final days near parturition. At birth the young 

 O. taurus do not have excessive amounts of yolk 

 within the digestive tract. We examined a 91.0 cm, 

 3.75 kg dead female pup (Fig. 17) from a 240 cm 

 female O. taurus held captive since 21 August 1980, 

 in a display tank ("Shark Encounter") at Sea World 

 of Orlando. The pup died immediately after birth on 

 22 March 1981. The stomach and intestine of the 

 newborn shark were not distended with yolk, 

 although yolk was present. Another pup, born simul- 

 taneously with the other uterus, lived and is presently 

 on display (April 1983). 



Simultaneous to the decline in yolk consumption is 

 an increase in the size of the embryo's liver. The left 

 and right lobes of the liver of the specimen from Sea 



World of Orlando measured 20.3 and 23.7 cm, re- 

 spectively, with a total liver weight of 372 g(9.9% of to- 

 tal body weight). Cadenat (1956) found the liver of a 

 near-term embryo to be relatively large, contributing 

 6.43% of the total body weight, in a 110 cm specimen. 

 The large liver in the near-term embryo compares 

 favorably with the largest liver recorded in adults at 

 7.54% total body weight (Cadenat 1956). A similar 

 condition of large liver size and reduced yolk con- 

 sumption has been observed in a near-term oophagous 

 embryo (97 cm TL) of Isurus paucus (Gilmore in 

 press). 



The increase in size of the embryo's liver corre- 

 sponds to an observed decline in maternal ovarian ac- 

 tivity and ovary size near the end of gestation 

 (Springer 1948). The liver of the pregnant near-term 

 female sand tiger shark also reaches a minimum size 

 at this time (2.88% total body weight, Cadenat 1956), 

 revealing the maximum uilization of the adult's nutri- 

 tive materials to support the two large, ravenous 

 embryos. 



Nutritional supplies stored within the embryo's 

 liver can then be utilized during the last few days of 

 gestation and after birth preceding the first capture 

 of prey. The surviving newborn female 0. taurus from 

 Sea World of Orlando did not eat until 25 d after 

 birth. She first ate (two pieces of clam) a day after she 

 attacked and killed another small shark (Diakis 

 semifasciata, Frank Murru"). After the initial feeding 

 the young sand tiger shark ate dead clams, squid, and 

 fish (blue runner, Caranx crysos, sardines, herrings, 

 "smelt", and mackerel) during daily feeding 

 periods. 



Fortunately O. taurus has been kept in captivity for 

 extended periods (up to 10 yr, 2 mo; R. van der 

 Elst 12 ). Several births have taken place both in a 

 South African aquarium (van der Elst footnote 12) 

 and American aquaria (Wood footnote 9; Murru foot- 

 note 11). Wood (footnote 9) made the following ob- 

 servations of the birth of O. taurus pups in an 

 aquarium at Marineland, St. Augustine, Fla., on 15 

 February 1959 from a female captured 1 1 November 

 1958 (Fig. 18): 



"The head of the first pup was first observed 

 about 0945 extending3 to 4 inches (7. 6 to 10.2 cm] 

 from the cloaca. The head came out a little further 

 during the next 30 minutes. The pup was born 

 c. 1015. 



'"A. F. McBride, formerly with Marineland Inc., St. Augustine, Fla., 

 pers. commun, 8 Nov. 1947 to Stewart Springer, Mote Marine Lab.. 

 Sarasota, FL 33577. 



"F. Murru, Curator of Fishes, Sea World of Orlando, FL 32809, 

 pers. commun. 1981. 



|: R. van der Elst, S. Afr. Assoc. Mar. Biol. Res., Durban, South 

 Africa, pers. commun. 1977. 



218 



