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Fusion of locomotor maneuvers, and improving sensory capabilities, give rise to the flexible homing strikes of juvenile zebrafish.

Westphal RE, O'Malley DM - Front Neural Circuits (2013)

Bottom Line: At 5 days post-fertilization and 4 mm in length, zebrafish larvae are successful predators of mobile prey items.Neomycin ablation of lateral line hair cells reduced the accuracy of strikes and overall feeding rates, especially when neomycin-treated larvae and juveniles were placed in the dark.Darkness by itself reduced the distance from which strikes were launched, as visualized by infrared imaging.

View Article: PubMed Central - PubMed

Affiliation: Department of Natural Sciences, North Shore Community College Lynn, MA, USA.

ABSTRACT
At 5 days post-fertilization and 4 mm in length, zebrafish larvae are successful predators of mobile prey items. The tracking and capture of 200 μm long Paramecia requires efficient sensorimotor transformations and precise neural controls that activate axial musculature for orientation and propulsion, while coordinating jaw muscle activity to engulf them. Using high-speed imaging, we report striking changes across ontogeny in the kinematics, structure and efficacy of zebrafish feeding episodes. Most notably, the discrete tracking maneuvers used by larval fish (turns, forward swims) become fused with prey capture swims to form the continuous, fluid homing strikes of juvenile and adult zebrafish. Across this same developmental time frame, the duration of feeding episodes become much shorter, with strikes occurring at broader angles and from much greater distances than seen with larval zebrafish. Moreover, juveniles use a surprisingly diverse array of motor patterns that constitute a flexible predatory strategy. This enhances the ability of zebrafish to capture more mobile prey items such as Artemia. Visually-guided tracking is complemented by the mechanosensory lateral line system. Neomycin ablation of lateral line hair cells reduced the accuracy of strikes and overall feeding rates, especially when neomycin-treated larvae and juveniles were placed in the dark. Darkness by itself reduced the distance from which strikes were launched, as visualized by infrared imaging. Rapid growth and changing morphology, including ossification of skeletal elements and differentiation of control musculature, present challenges for sustaining and enhancing predatory capabilities. The concurrent expansion of the cerebellum and subpallium (an ancestral basal ganglia) may contribute to the emergence of juvenile homing strikes, whose ontogeny possibly mirrors a phylogenetic expansion of motor capabilities.

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“Dark Feeding” episode of a 39 dpf, juvenile zebrafish. Video was collected at 250 frames per second under IR-illumination and representative frames are shown. (A) Three frames, each separated by 400 ms, show the motion of the prey item which occurs before initiation of the feeding episode. Note that the Artemia is moving in a caudal to rostral direction as highlighted by the white circle. (B) Dark feeding by this juvenile is documented via select frames showing locomotor (fin) movements (arrows) and strike attempts, i.e., jaw protrusions (asterisks), with success occurring on the third attempt. The fins are very thin and light and so difficult to see in still photos, but are more apparent when viewing movie files. Note that the jaw protrusion occurring at 968 ms can be seen as a light, anterior extension of the snout, which is not occurring in the frame just above it (at 840 ms).
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Figure 11: “Dark Feeding” episode of a 39 dpf, juvenile zebrafish. Video was collected at 250 frames per second under IR-illumination and representative frames are shown. (A) Three frames, each separated by 400 ms, show the motion of the prey item which occurs before initiation of the feeding episode. Note that the Artemia is moving in a caudal to rostral direction as highlighted by the white circle. (B) Dark feeding by this juvenile is documented via select frames showing locomotor (fin) movements (arrows) and strike attempts, i.e., jaw protrusions (asterisks), with success occurring on the third attempt. The fins are very thin and light and so difficult to see in still photos, but are more apparent when viewing movie files. Note that the jaw protrusion occurring at 968 ms can be seen as a light, anterior extension of the snout, which is not occurring in the frame just above it (at 840 ms).

Mentions: While zebrafish are primarily visual predators, they do feed in the dark, albeit at lower rates. Using infrared (IR) illumination, zebrafish and prey movements were recorded in the dark. A representative episode is shown in the montages in Figure 11, where an Artemia (inside white circle) can be seen swimming alongside a juvenile for about 800 ms (Figure 11A). Then, the zebrafish abruptly turns and makes several attempts to capture the Artemia, beginning about the second frame in Figure 11B (pectoral fin movements are indicated by arrows). Two unsuccessful strikes (indicated by jaw protrusions, asterisks) occur at 856 and 900 ms, while a third strike at 968 ms was successful.


Fusion of locomotor maneuvers, and improving sensory capabilities, give rise to the flexible homing strikes of juvenile zebrafish.

Westphal RE, O'Malley DM - Front Neural Circuits (2013)

“Dark Feeding” episode of a 39 dpf, juvenile zebrafish. Video was collected at 250 frames per second under IR-illumination and representative frames are shown. (A) Three frames, each separated by 400 ms, show the motion of the prey item which occurs before initiation of the feeding episode. Note that the Artemia is moving in a caudal to rostral direction as highlighted by the white circle. (B) Dark feeding by this juvenile is documented via select frames showing locomotor (fin) movements (arrows) and strike attempts, i.e., jaw protrusions (asterisks), with success occurring on the third attempt. The fins are very thin and light and so difficult to see in still photos, but are more apparent when viewing movie files. Note that the jaw protrusion occurring at 968 ms can be seen as a light, anterior extension of the snout, which is not occurring in the frame just above it (at 840 ms).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3675323&req=5

Figure 11: “Dark Feeding” episode of a 39 dpf, juvenile zebrafish. Video was collected at 250 frames per second under IR-illumination and representative frames are shown. (A) Three frames, each separated by 400 ms, show the motion of the prey item which occurs before initiation of the feeding episode. Note that the Artemia is moving in a caudal to rostral direction as highlighted by the white circle. (B) Dark feeding by this juvenile is documented via select frames showing locomotor (fin) movements (arrows) and strike attempts, i.e., jaw protrusions (asterisks), with success occurring on the third attempt. The fins are very thin and light and so difficult to see in still photos, but are more apparent when viewing movie files. Note that the jaw protrusion occurring at 968 ms can be seen as a light, anterior extension of the snout, which is not occurring in the frame just above it (at 840 ms).
Mentions: While zebrafish are primarily visual predators, they do feed in the dark, albeit at lower rates. Using infrared (IR) illumination, zebrafish and prey movements were recorded in the dark. A representative episode is shown in the montages in Figure 11, where an Artemia (inside white circle) can be seen swimming alongside a juvenile for about 800 ms (Figure 11A). Then, the zebrafish abruptly turns and makes several attempts to capture the Artemia, beginning about the second frame in Figure 11B (pectoral fin movements are indicated by arrows). Two unsuccessful strikes (indicated by jaw protrusions, asterisks) occur at 856 and 900 ms, while a third strike at 968 ms was successful.

Bottom Line: At 5 days post-fertilization and 4 mm in length, zebrafish larvae are successful predators of mobile prey items.Neomycin ablation of lateral line hair cells reduced the accuracy of strikes and overall feeding rates, especially when neomycin-treated larvae and juveniles were placed in the dark.Darkness by itself reduced the distance from which strikes were launched, as visualized by infrared imaging.

View Article: PubMed Central - PubMed

Affiliation: Department of Natural Sciences, North Shore Community College Lynn, MA, USA.

ABSTRACT
At 5 days post-fertilization and 4 mm in length, zebrafish larvae are successful predators of mobile prey items. The tracking and capture of 200 μm long Paramecia requires efficient sensorimotor transformations and precise neural controls that activate axial musculature for orientation and propulsion, while coordinating jaw muscle activity to engulf them. Using high-speed imaging, we report striking changes across ontogeny in the kinematics, structure and efficacy of zebrafish feeding episodes. Most notably, the discrete tracking maneuvers used by larval fish (turns, forward swims) become fused with prey capture swims to form the continuous, fluid homing strikes of juvenile and adult zebrafish. Across this same developmental time frame, the duration of feeding episodes become much shorter, with strikes occurring at broader angles and from much greater distances than seen with larval zebrafish. Moreover, juveniles use a surprisingly diverse array of motor patterns that constitute a flexible predatory strategy. This enhances the ability of zebrafish to capture more mobile prey items such as Artemia. Visually-guided tracking is complemented by the mechanosensory lateral line system. Neomycin ablation of lateral line hair cells reduced the accuracy of strikes and overall feeding rates, especially when neomycin-treated larvae and juveniles were placed in the dark. Darkness by itself reduced the distance from which strikes were launched, as visualized by infrared imaging. Rapid growth and changing morphology, including ossification of skeletal elements and differentiation of control musculature, present challenges for sustaining and enhancing predatory capabilities. The concurrent expansion of the cerebellum and subpallium (an ancestral basal ganglia) may contribute to the emergence of juvenile homing strikes, whose ontogeny possibly mirrors a phylogenetic expansion of motor capabilities.

Show MeSH
Related in: MedlinePlus