QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online March 8, 2005
Journal of Experimental Biology 208, 831-842 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01406

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mussi, M. Articles by Domenici, P. Search for Related Content PubMed PubMed Citation Articles by Mussi, M. Articles by Domenici, P. Social Bookmarking                         What's this?

Visual cues eliciting the feeding reaction of a planktivorous fish swimming in a current

Martina Mussi^1,2, William N. McFarland³ and Paolo Domenici^4,2,*

¹ Department of Biology, University of Victoria, PO Box 3020 STN CSC, Victoria, British Columbia, Canada
² International Marine Centre, Loc. Sa Mardini, 09072 Torregrande, Oristano, Italy
³ School of Aquatic and Fisheries Sciences, and Friday Harbor Laboratory, University of Washington, Friday Harbor WA 98250, USA
⁴ CNR-IAMC, Loc. Sa Mardini, 09072 Torregrande, Oristano, Italy

View larger version (15K): [in a new window]   Fig. 1. Flume tank used in the experiments seen from the side (as viewed by the camera). (A) working section, (B) collimators, (C) mirror at 45°, providing top view of the fish, (D) pump, (E) Catch screen. The shaded rectangular section indicates the approximate field of view of the camera.

View larger version (62K): [in a new window]   Fig. 2. Images of semi-transparent (natural) (A, under dark-field illumination; C, under bright-field illumination) and darkened (B, under dark-field illumination; D, under bright-field illumination) Artemia. Specimens were photographed using a photomicroscope (Wild M400 Photomakroskop) onto Fuji Sensia 100 iso slide film, using two synchronised flashes (Sunpak Auto 383 Super) and a 64x magnification. Scanned (jpg) imaged were obtained using a Scanner UMAX Mirage II Se, at a 200x200 dpi resolution and 342x537 pixels. These images do not necessarily reflect the Artemia as perceived by the fish.

View larger version (17K): [in a new window]   Fig. 3. Geometry of the particle detection and capture in three dimensions. The direction of the current is indicated by empty arrows. A fish's initial detection response is triggered at TL, and the fish's first visible reaction to an approaching food particle occurs at TR (i.e. response latency occurs between TL and TR). The arrow between TL and TR indicates the distance covered by the particle during the response latency. The food particle is captured at TC, and the distance covered between TR and TC corresponds to Yforward. Various particles are drawn at TC because the particle at TC may be upstream or downstream relative to the fish's eyes at TR (data not shown). X'lateral is the lateral distance in the horizontal plane. Xlateral is the overall lateral distance between the fish's eyes and the axis of motion of the prey along the current. Zvertical and Dtotal are the vertical distance and the total distance, in three dimensions, between fish's eyes and the particle at TR, respectively. Alpha () is the angle between the current direction and Dtotal. Beta (ß) is the angular size of the plankton as seen by the fish.

View larger version (20K): [in a new window]   Fig. 4. (A) The relationship between angular size (ßR) and Yforward at various theoretical values of Xlateral. The graph is valid for all speeds, because angular size is not affected by current speed (Uc). Any given value of ßR is reached at decreasing values of Yforward as Xlateral increases. (B) The relationship between loom R and Yforward (the particle distance upstream at the time of TR), at various theoretical values of Xlateral, at the intermediate current speed used in darkened conditions. At Xlateral=0, R is always highest. Horizontal line represents the average experimental values of R found in darkened conditions at intermediate Uc. R is reached at smaller values of Yforward as Xlateral values increase. (C) The relationship between angular velocity R and Yforward at various theoretical values of Xlateral, at the intermediate current speed used for semi-transparent Artemia. At Xlateral=0, R would be equal to zero and it is not represented. Horizontal line represents the average experimental values of R found for semi-transparent Artemia at intermediate Uc. Average R is reached at increasing values of Yforward as Xlateral values increase.

View larger version (10K): [in a new window]   Fig. 5. Frequency distribution of reaction distance Dtotal over all current speeds for both semi-transparent (white bars) and darkened (black bars) Artemia.

View larger version (25K): [in a new window]   Fig. 6. Angular velocity R (black bars), loom R (white bars) and angular size ßR (grey bars) at different current speeds in the semi-transparent (A) and darkened (B) conditions; error bars show S.E.M.

View larger version (14K): [in a new window]   Fig. 7. Frequency distribution of particle lateral distance (Xlateral) in the darkened (black bars) and semi-transparent conditions (white bars) over all current speeds.

View larger version (22K): [in a new window]   Fig. 8. Experimental values of Yforward and Xlateral at low, intermediate and high current speed in semi-transparent (A, B, C, respectively) and darkened (D, E, F, respectively). Blue, red and green lines represent values corresponding to a constant loom, angular velocity and angular size, respectively (i.e. the average loom, angular velocity and angular size for each given speed, respectively).

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter