Bay squid, continued 



Age and Size of Adults : The life cycle of this species is 

 approximately one year (Hargis and Hanlon 1984). 

 Males are sexually mature in about 6 months at a 

 mantle length (ML) of about 40-60 mm (=1 3 g); females 

 at 8 months when they are about 70-80 mm ML (=30 g) 

 (Hixon 1 980a, Hixon 1 980b, Hargis and Hanlon 1 984). 

 Males appear to mature at slightly smaller sizes (32 

 mm ML) than females (63 mm ML) (Benson 1982). 

 Adults have been collected with ML's up to 85 mm for 

 males and 1 1 mm forfemales (Fischer 1 978). Growth 

 morphometry of bay squid in Delaware Bay is de- 

 scribed by Haefner (1964). 



Food and Feeding 



Trophic mode : Juveniles and adults are carnivores, 

 consuming a variety of fish and crustaceans. Their 

 high feeding and growth rates make this species an 

 important predator in coastal estuaries (Hargis and 

 Hanlon 1984). Preferred prey species typically seem 

 to be highly visible nektonic species (Hargis 1979a, 

 Hargis 1979b). The bay squid and cephalopods pos- 

 sess a sophisticated receptor system analogous to the 

 lateral line system in fishes and amphibians for the 

 detection of small water movements (Budelmann and 

 Bleckmann 1 988). This sensory apparatus could allow 

 the normally visually oriented bay squid to locate prey 

 under low visibility conditions (e.g. murky or deep 

 water, or night). Feeding methods of this species are 

 typical of loliginid squid (Hanlon et al. 1 983, Turk pers. 

 comm.). Prey are seized with the squid's tentacles that 

 are thrust quickly forward by means of an internal 

 hydraulic mechanism. The captured animal is then 

 "reeled in" and positioned near the mouth by retracting 

 the tentacles. Prey items (e.g. fish) are injected with 

 venom usually through bites behind the head with the 

 squid's parrot-like beak. The venom acts as a tranquil- 

 izer that paralyzes the prey. Once fish prey are 

 paralyzed, the squid consumes the viscera, and then 

 strips the flesh from the animal by means of perforating 

 bites down the animal's sides. Shrimp prey are com- 

 pletely eaten except for the head and the exoskeleton. 

 A typical meal is cleared through the digestive system 

 in approximately 30 minutes. 



Food Items : Planktonic copepods are likely the natural 

 prey for paralarval bay squid (Vecchione 1 991 ). Juve- 

 niles and adults feed on larger prey, mostly nektonic 

 fishes and shrimps. Juveniles have a slight preference 

 forcrustaceans, while adults seem to preferfish (Hargis 

 and Hanlon 1984). Adults feed primarily on juvenile 

 striped mullet, tidewatersilversides, and Atlantic croaker 

 in the upper regions of the water column. They also 

 show some preference for white shrimp. If prey move 

 to the bottom without being detected they are not 

 pursued. Juvenile bay squid prefer fish and shrimp 

 equal to or smaller than their own size. Tidewater 

 silversides, sheepshead minnows, and sailfin mollies 



have been observed as natural foods (Hargis 1979a, 

 Hargis 1979b, Hixon 1980a). Seagrass has also been 

 reported as a food item (Benson 1982). Polychaetes 

 have also been reported as occurring in bay squid 

 stomach contents (Vecchione 1991a). 



Biological Interactions 



Predation : The bay squid is preyed upon by larger 

 fishes. 



Factors Influencing Populations : Greater abundances 

 of bay squid are correlated with lower salinities and 

 higher temperatures with respect to other squid spe- 

 cies in the Gulf of Mexico (Hixon 1980). This species 

 is most numerous in waters <30 m deep. 



Personal communications 



Turk, Phil. Marine Biomedical Institute, University of 

 Texas Medical Branch, Galveston, TX. 



Forsythe, John. Marine Biomedical Institute, Univer- 

 sity of Texas Medical Branch, Galveston, TX. 



Vecchione, Michael. NOAA NMFS Systematics Lab., 

 National Museum of Natural History, Washington, DC. 



References 



Andrews, J. 1981. Texas Shells, A Field Guide. 

 University of Texas Press, Austin, TX, 175 p. 



Bane, G.W., R.L. Allen, J.H. Render, T. Farooqi, and 

 A.C.Wagner. 1985. Biology, ecology and economics 

 of squid and butterfish of the northern Gulf of Mexico. 

 Quarterly Report, July 1 985, Coast. Fish. Inst., Center 

 for Wetlands Res., Louis. St. Univ., Baton Rouge, LA, 

 LSU-CFI-85-24, 126 p. 



Benson, N.G. (ed.) 1982. Life history requirements of 

 selected finfish and shellfish in Mississippi Sound and 

 adjacent areas. U.S. Fish Wildl. Serv. Biol. Rep., FWS/ 

 OBS-81/51,97p. 



Boletzky, S.V. 1986. Encapsulation of cephalopod 

 embryoes: a search for functional correlations. Am. 

 Malacol. Bull. 4:217-227. 



Budelmann, B.U., and H. Bleckmann. 1988. A lateral 

 line analogue in cephalopods: water waves generate 

 microphonic potentials in the epidermal head lines of 

 Sepia and Lolliguncula. J. Comp. Physiol. A 164:1-5. 



Dillion, L.S., and R.O. Dial. 1962. Notes on the 

 morphology of the common Gulf squid Lolliguncula 

 brevis (Blainville). Tex. J. Sci. 14:156-166. 



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