Functional Morphology of Prey Ingestion by Placetron wosnessenskii Schalfeew Zoeae (Crustacea: Anomura: Lithodidae)

Abstract

The relationship between the morphology and functions of the feeding appendages of first-stage zoeae of the lithodid crab Placetron wosnessenskii Schalfeew during ingestion is explored in this study. The preoral chambers of these zoeae are bordered on all sides, with the labrum and mandibles forming the anterior borders, the paragnaths and sternal projection together creating the posterior boundaries, and the maxillules forming the sides. The maxillules are the sole pair of appendages responsible for prey manipulation immediately preceding ingestion. Maxillules are capable of remarkable plasticity of movement, enabling them to grasp, control, and redirect violently struggling prey (Artemia sp. metanauplii). The asymmetrical mandibles tear and grind the prey, working against each other with rotating motions. Two separate ratchet-like coordinations of the appendages were seen, each of which enabled the zoea to maintain a firm grasp on the prey while renewing points of leverage for ingestion. The mandibles hold prey in position while the maxillules regrab it to push it farther into the mouth. Similarly, the labrum holds the prey while the mandibles prepare for a new grinding rotation. Capture and ingestion of an algal cell by a rapid outward flinging and inward clasping of the mouthparts was seen in one videotaped sequence. Gut fluorescence after introduction of various algal species reveals an ability to ingest a range of particle sizes. This plasticity of feeding behaviors allows the zoeae to ingest a range of food items, and thus meet their nutritional needs.

Functional morphology of mouthparts and digestive system during larval development of the cleaner shrimp Lysmata amboinensis (de Man, 1888)

“…late stage larvae the primary function of the maxillae may be a respiratory one, with the long plumose setae on the scaphognathite creating a current flow over the developing gills. The shorter plumose setae on the endites may act as a net to prevent entry of particles to the branchial chamber (Farmer, 1974;Factor, 1978;Crain, 1999).…”

“…The software used was Axiovision v4.5. The terminology of Crain (1999) was followed for the description of the mouthpart setae, with Factor (1978) used as an additional source for setal types not included in Crain (1999).…”

“…The link between functional morphology and diet has been well documented, with many feeding studies connecting the anatomy of the mouthparts and digestive system with behavioral observations (Roberts, 1968;Schaefer 1970;Greenwood, 1972;Caine 1975;Barker and Gibson, 1978;Schembri, 1982;Alexander and Hindley, 1985;Paffenhofer and Lewis, 1989;Lavalli and Factor, 1992;Mcmillan et al, 1997;Crain, 1999;Nelson et al, 2002;Drumm, 2004;Richter and Kornicker, 2006). The feeding strategy for a particular species can be assessed through the study of mouthparts and gut.…”

Discrimination in ingestion of protistan prey by larval crabs

“…Prey capture by crab larvae does not appear to require use of their well-developed eyes (Harvey & Epifanio 1997, Sulkin et al 1998a) and occurs over a wide range of prey sizes (from at least 5 to 250 µm; Lehto et al 1998). Larger prey typically are grasped by the endites of the maxillules and pushed toward the mandibles where they are masticated and ingested (Crain 1999). It is possible that the protist Noctiluca, being as large as the largest metazoan prey typically used in laboratory culture of crab larvae, are handled in a similar way.…”

Wood-based diet and gut microflora of a galatheid crab associated with Pacific deep-sea wood falls

“…Some authors have tried to link function to setal morphology, but sometimes similar morphologies fulWll several possible functions (Factor 1978;Schembri 1982;Felgenhauer and Abele 1985;Crain 1999;Stamhuis et al 1998;Coelho and Rodrigues 2001;Garm and Høeg 2001). The literature suggests that serrate setae can play a role in chemosensitivity, cleaning, or food adhesion; cuspidate setae can play a role in grasping food; plumose setae are often involved in creating water currents important in respiration or suspension-feeding; and pappose setae do not participate in food handling but usually create setal barriers.…”