Robert Jan "Roy" van de Hoek, President
Ballona Institute
Los Angeles, California
roy@naturespeace.org
June 17, 2014
FEEDING AND ASSOCIATED FUNCTIONAL MORPHOLOGY
IN TAGELUS CALIFORNIANUS
AND FLORIMETIS OBESA (BIVALVIA: TELLINACEA
By
Ross H. Pohlo
Department of Biology,
California State University at Northridge
Northridge, California 91342 U.S.A

ABSTRACT
          A study was made comparing 2 species, Tagelus californianus (Conrad, 1837) and Florimetis obesa (Deshayes, 1855), with other members of the super family Tellinacea. The nature of their feeding was investigated and an attempt was made to relate aspects of their morphology to feeding behavior.
          Field and laboratory studies, particularly of the behavior of the inhalant siphon, and an analysis of mantle cavity and stomach contents were performed to ascertain the mode of feeding of these species.
          Tagelus californianus resembles suspension feeding bivalves by having large ctenidia which possess well developed marginal grooves, the outer demibranch is not upturned, the dorsal hood is large, incipient straining tentacles exist on the inhalant siphon, the animal is upright in the burrow and a mantle fold is lacking. The only major features common to this species and deposit feeders are separated siphons.
          Florimetis obesa resembles deposit feeders by having upturned outer demibranchs, the presence of a mantle fold, separate siphons which lack straining tentacles and the organism lies on its side. It resembles suspension feeders by having relatively large ctenidia.

INTRODUCTION
          As has been shown (Pohlo, 1969) there has been some confusion concerning the type of feeding that occurs in the super family Tellinacea.

MATERIALS AND METHODS
          Florimetis obesa and Tagelus californianus were collected at Newport Bay and Mugu Lagoon in Southern California. T. californianus was found in various fine to medium grained substrata and occurs in great abundance in the banks of small tidal channels. As described by Weymouth (1920) and Yonge (1952) the animal occurs upright in a permanent burrow that can reach a depth of 50 cm. Its range is from Humboldt Bay, California to Panama (McLean, 1969).

ACKNOWLEDGMENT
          I wish to thank Dr. Marvin Cantor and Dr. Joseph Moore for reading the manuscript.

LITERATURE CITED
BRAFIELD, A. W. & NEWELL, G. E. 1961. The behavior of Macoma balthica (L.) J. mar. bio. Assoc. U. K., 41: 81-87.
YONGE, CHARLES MAURICE.
1949. On the structure and adaptations of the Tellinacea, deposit-feeding Eulamellibranchia. Phil. Trans. Roy. Soc. London, Ser. B. 234: 29 - 76.

1952. Studies on Pacific coast Mollusks. IV. Observation on Siliqua patula Dixon and on the evolution within the Solenidae. Univ. Calif. Publ. Zool. 55: 421 - 438.