Feeding strategy of the megamouth shark <i>Megachasma pelagios</i> (Lamniformes: Megachasmidae)

Nakaya, Kazuhiro; Matsumoto, Rei; Suda, Kenta

doi:10.1111/j.1095-8649.2008.01880.x

Cited by 44 publications

(41 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These large gills would not be necessary in pump suspension-or engulfmentfeeding fishes, which filter by first creating a suction force to entrain zooplankton-rich water and then subsequently close their mouths to force this water over the gill rakers. This point is illustrated nicely by comparing the smaller gill morphology of a megamouth shark, Megachasma pelagios, which has been hypothesized to use an engulfment feeding strategy (Nakaya et al, 2008), with that of the large-gilled basking sharks (Bigelow and Schroeder, 1953) and whale sharks (Colman, 1997), which use, at least in part, ram suspension feeding. Though we had predicted that ram filtration efficiency would increase with gill size, we did not predict that the particle distribution would shift to that of a planktonic specialist without having to adjust the pore size of the filter.…”

Section: Discussionmentioning

confidence: 99%

Bottles as models: predicting the effects of varying swimming speed and morphology on size selectivity and filtering efficiency in fishes

Paig-Tran

Bizzarro

Strother

et al. 2011

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARYWe created physical models based on the morphology of ram suspension-feeding fishes to better understand the roles morphology and swimming speed play in particle retention, size selectivity and filtration efficiency during feeding events. We varied the buccal length, flow speed and architecture of the gills slits, including the number, size, orientation and pore size/permeability, in our models. Models were placed in a recirculating flow tank with slightly negatively buoyant plankton-like particles (~20-2000m) collected at the simulated esophagus and gill rakers to locate the highest density of particle accumulation. Particles were captured through sieve filtration, direct interception and inertial impaction. Changing the number of gill slits resulted in a change in the filtration mechanism of particles from a bimodal filter, with very small (≤50m) and very large (>1000m) particles collected, to a filter that captured medium-sized particles (101-1000m). The number of particles collected on the gill rakers increased with flow speed and skewed the size distribution towards smaller particles (51-500m). Small pore sizes (105 and 200m mesh size) had the highest filtration efficiencies, presumably because sieve filtration played a significant role. We used our model to make predictions about the filtering capacity and efficiency of neonatal whale sharks. These results suggest that the filtration mechanics of suspension feeding are closely linked to an animal's swimming speed and the structural design of the buccal cavity and gill slits. Supplementary material available online at

show abstract

Section: Discussionmentioning

confidence: 99%

Bottles as models: predicting the effects of varying swimming speed and morphology on size selectivity and filtering efficiency in fishes

Paig-Tran

Bizzarro

Strother

et al. 2011

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…Those swarms formed at the surface in daytime. Nakaya et al (2008) suggested that the megamouth shark performs engulfment feeding like a rorqual whale, and is morphologically distinguished from a basking shark and a whale shark in the buccal structure which is composed of a larger bucco-pharyngeal cavity and stretchable skin on the ventral and lateral sides of the head in the megamouth shark. The present results on stomach contents and previous information suggest that the megamouth specimen was caught soon after feeding on a surface swarm of E. pacifica.…”

mentioning

confidence: 99%

Stomach contents of a megamouth shark Megachasma pelagios from the Kuroshio Extension: evidence for feeding on a euphausiid swarm

Sawamoto

Matsumoto

2012

Plankton Benthos Res

View full text Add to dashboard Cite

Abstract:More than 50 specimens of the megamouth shark Megachasma pelagios have been reported so far, but biological observations on the species are still limited. We examined a female megamouth specimen that was captured by the bonito purse seine fishery in the Kuroshio Extension in July 2007 and donated to the Okinawa Churaumi Aquarium. The specimen was an immature female, 3,667 mm in total length and 361 kg in weight. The stomach contents measured 2,200 mL excluding the portion that was lost from the specimen before measurement. Detailed examination of a small part (14.6 mL) of the stomach contents revealed undamaged worm-like organisms, 10 partially damaged euphausiids and abundant fragmented pieces of euphausiids. The worm-like organisms were probably parasites such as tapeworms. The partially damaged euphausiids were identified as Euphausia pacifica except for one individual of Nematoscelis difficilis. Based on the number of fragmented right mandibles, which were less damaged than the other fragmented appendages, the total number of euphausiids in the stomach contents is estimated to be at least 18,000 individuals. The high abundance of euphausiids in the stomach contents suggests that the present specimen has fed on a swarm of E. pacifica in an oceanic area.

show abstract

“…With each scenario presented here, once a desired level of electrosensory stimuli has been achieved, ingestion of prey would then follow using a gulp-and suction-feeding mechanism (Nakaya et al 2008) to consume all the available planktonic prey in the vicinity of the head, thereby maximising the efficiency of each feeding event.…”

Section: Discussionmentioning

confidence: 99%

“…Unlike other planktivorous sharks such as Cetorhinus maximus (basking shark) and Rhincodon typus (whale shark), M. pelagios is thought to adopt a unique method of filter feeding. Instead of swimming continuously with its enormous mouth wide open, filtering water for plankton and jellyfish, M. pelagios is thought to attract prey with a bioluminescent strip along its upper jaw (Taylor et al 1983) -although this has not yet been supported with histological evidence (Nakaya et al 2008) -and then engulf it in a single motion, similar to the feeding mechanism of some baleen whales (Compagno 1990, Nakaya et al 2008). This active method of ingesting prey is thought to be due to the restricted internal gill openings and jaw morphology of M. pelagios sharks (Compagno 1990, Nakaya et al 2008.…”

Section: Introductionmentioning

confidence: 99%

“…Instead of swimming continuously with its enormous mouth wide open, filtering water for plankton and jellyfish, M. pelagios is thought to attract prey with a bioluminescent strip along its upper jaw (Taylor et al 1983) -although this has not yet been supported with histological evidence (Nakaya et al 2008) -and then engulf it in a single motion, similar to the feeding mechanism of some baleen whales (Compagno 1990, Nakaya et al 2008). This active method of ingesting prey is thought to be due to the restricted internal gill openings and jaw morphology of M. pelagios sharks (Compagno 1990, Nakaya et al 2008. It is thought that swimming with its mouth open would create a negative pressure, whereby water and prey would be pushed aside, due to its densely packed papillose gill rakers and relatively small internal gill rakers (Compagno 1990).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electrosensory pore distribution and feeding in the megamouth shark Megachasma pelagios (Lamniformes: Megachasmidae)

Kempster¹,

Collin²

2011

Aquat. Biol.

View full text Add to dashboard Cite

The megamouth shark Megachasma pelagios is a rare, large filter-feeding shark. Little to nothing is known of its sensory biology, particularly in relation to its feeding behaviour. We describe the abundance and distribution of ampullary pores over the head and propose that both the spacing and orientation of electrosensory pores enables M. pelagios to use passive electroreception to maximise feeding efficiency. KEY WORDS: Ampullae of Lorenzini · Electroreception · Filter feeding · Megamouth sharkResale or republication not permitted without written consent of the publisher Aquat Biol 11: 225-228, 2011 whereby water and prey would be pushed aside, due to its densely packed papillose gill rakers and relatively small internal gill rakers (Compagno 1990).M. pelagios tracked off the coast of California performed vertical migrations with the onset of sunrise and sunset (Nelson et al. 1997). This crepuscular migration allowed M. pelagios to consistently sample the water column at a specific level of illumination, with the shark staying at shallow depth at night (12 to 25 m) and in the deep during the day (120 to 166 m), but still well above the sea bed, which is at 700 to 850 m (Nelson et al. 1997). M. pelagios was thought to be following an isolume of 0.4 lux, the same light cue used by its vertically migrating prey (Nelson et al. 1997). As a result, a correlation was found between the diel depth distribution of M. pelagios and the vertically migrating krill Euphausia pacifica, which is common in southern California waters (Nelson et al. 1997). The highest night-time concentration of adults and juveniles of E. pacifica was reported to be between the surface and 40 m, with a deeper adult daytime peak located at 200 m (Brinton 1962, Nelson et al. 1997. MATERIALS AND METHODSA specimen of Megachasma pelagios (referred to as Megamouth 3) 5 m in length was stranded in Mandurah, Western Australia, in 1988 (Berra & Hutchins 1990. Access to the shark was given during its relocation from the Museum of Western Australia to the Western Australian Maritime Museum in Fremantle. The specimen had been fixed in 70% ethanol for 22 yr and, although it was apparent that some degree of tissue shrinkage had occurred, the ampullary pores were easily distinguishable from the lateral line pores, given the obvious size difference. Due to limited access to the specimen during this time, the lateral line pores could not be counted and/or their distribution mapped. No dissection of the ampullary pores was allowed, negating any chance of histological analysis. Pores were counted in situ, and photographs were used to produce the pore map presented here, with the aid of a Corel-DRAW graphics suite (Fig. 1). RESULTSA total of 225 ampullary pores were present on the head of Megachasma pelagios (Fig. 1), with significantly more pores (75%) located on the dorsal (D) surface of the head than the ventral (V, 4%) and lateral (L, 21%) surfaces combined (25%; see Table 1). Ampullary pores were found in the most dense assem- (Table 1). Pore fi...

show abstract

Feeding strategy of the megamouth shark Megachasma pelagios (Lamniformes: Megachasmidae)

Cited by 44 publications

References 10 publications

Bottles as models: predicting the effects of varying swimming speed and morphology on size selectivity and filtering efficiency in fishes

Bottles as models: predicting the effects of varying swimming speed and morphology on size selectivity and filtering efficiency in fishes

Stomach contents of a megamouth shark Megachasma pelagios from the Kuroshio Extension: evidence for feeding on a euphausiid swarm

Electrosensory pore distribution and feeding in the megamouth shark Megachasma pelagios (Lamniformes: Megachasmidae)

Contact Info

Product

Resources

About