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1.
Feeding habits of tropical fish larvae were analysed in a comparative study of four species (Scorpaenodes sp., Carangoides sp., Acanthocepola sp. and Cynoglossus sp.) from the Andaman Sea. We investigated morphological characteristics and their potential influence on larval feeding, and looked for common patterns in larval prey preference. Gut contents of a total of 300 larvae were examined and compared with local zooplankton composition. The feeding habits of the investigated larvae shared a number of characteristics. During ontogeny both the preferred prey size and the number of prey in the gut increased, and across all larval size classes the relative prey size spectrum stayed constant, of approximately the same magnitude for all four species. On the other hand, larval feeding also differed in a number of aspects, especially differences in the taxonomic composition of preferred prey were apparent. Scorpaenodes sp. preferred abundant and large prey taxa, Acanthocepola sp. and Carangoides sp. preferred large, but less common prey taxa, while Cynoglossus sp., which had the relatively smallest mouth size, preferred smaller sized prey groups. Hence, the findings indicate that from an offset of common characteristics, especially related to prey size preference, larvae have their individual feeding patterns related to specific morphology and patterns of distribution.Communicated by M. Kühl, Helsingør 相似文献
2.
We tested the influence of limiting access to prey on larval development of the crabs Cancer magister and Hemigrapsus oregonensis by raising their Stage 1 larvae in the laboratory on different prey densities and with various periods of access to prey.
Experiments were conducted in 1995 and 1996 at the Shannon Point Marine Center in Anacortes, Washington, USA. Our results
show that crab larvae do not require continuous access to prey for optimal development nor do they appear to require light
for prey capture. Survival and duration of Stage 1 C. magister fed continuously on only one-fourth the amount of the control density of prey and those fed at the control density for only
6 h per day were the same as for larvae fed continuously at the control density (20 ml−1). Larvae with cyclic access to prey at the control density for 24 h and then starved for 72 h showed significantly lower
survival and longer instar duration to Stage 2. Experiments on Stage 1 H. oregonensis which investigated a combination of prey density, period of access to prey and light/dark conditions during feeding revealed
that survival decreased with decreasing prey density or with decreasing feeding period, but no differences were observed during
periods of limited prey availability as a function of light or dark conditions. Stage duration was not affected by reduced
prey density nor by the light/dark condition at the time of feeding, but it was prolonged when the period of access to prey
was limited. The period of access to prey did not affect the weight of Day 1 Stage 2 larvae. Larvae fed high densities of
prey for 4 h followed by 20 h of reduced-density diet exhibited the same survival and stage duration as controls that were
continuously fed high-density prey. Our results define sub-optimal diets that can be used experimentally to determine the
nutritional contributions made by naturally-occurring prey organisms during larval development in the two species. In nature,
larvae may satisfy nutritional requirements through periodic encounters with dense prey patches during vertical migrations
by day or night.
Received: 12 August 1997 / Accepted: 5 February 1998 相似文献
3.
P. Munk 《Marine Biology》1995,122(2):205-212
Fish larvae meet diverse environmental conditions at sea, and larval growth and chance of survival depend on a flexible response to environmental variability. The present study focuses on the flexibility of the foraging behaviour of larval cod in a series of laboratory experiments on larval search activity, prey selectivity, and hunger in a variable prey environment. Gadus morhua eggs were collected in March 1992 and 1993 from the Kattegat area, Denmark, fertilised and incubated in the laboratory. After hatching, the larvae were transferred to rearing tanks of 172 litres. The behaviour of larvae (6 to 7 mm long) was observed visually, and prey attacks, swimming activity and gut contents were registered across a range of 1 to 120 copepod nauplii l-1. When prey density decreased, larvae increased their swimming activity, increased their responsiveness to prey (distance of reaction) and decreased their prey size selectivity. Behavioural response was to a large degree determined by the level of hunger, represented by the number of newly ingested prey in the gut. The findings show that cod larvae have a flexible response to changes in feeding conditions and imply that larvae can grow and survive even in the lower range of (mean) prey densities measured at sea. 相似文献
4.
Feeding ecology of Greenland halibut (Gr. halibut) (Reinhardtius hippoglossoides) and sandeel (Ammodytes sp.) larvae on the West Greenland shelf was studied during the main part of the productive season (May, June and July). Copepods were the main prey item for larval Gr. halibut and sandeel, constituting between 88 and 99% of the ingested prey biomass. For both species, absolute size of preferred prey increased during ontogeny. However, preferred copepod size in relation to larval length differed markedly. In Gr. halibut, the relative size of the prey declined during growth of the larvae, while it remained constant for sandeel at a level of 2.7% of larval length. This led to a reduction in prey niche overlap between the two species. The available prey copepod biomass differed distinctly across the shelf area. In May, the prey density of Gr. halibut was the highest in the off-shelf area in Davis Strait. In June and July, the prey-rich areas for both species were mainly located at the slopes of the banks and at the shelf break area. Gut fullness was higher in these areas than in neighbouring areas, suggesting that the larval food resource could be scarce. The feeding ecology of Gr. halibut and sandeel could explain why larval abundance indices of the two species have historically shown opposite responses to yearly environmental conditions and total zooplankton occurrence. 相似文献
5.
A. Kellermann 《Marine Biology》1990,106(2):159-167
The feeding dynamics of larvae of the Antarctic fishNototheniops larseni were analyzed from data collected over three years in Bransfield Strait and adjacent waters (Antarctica). Seasonal feeding was examined from 1977/1978 (November–March). The diel feeding cycle was investigated during a 96 h station established in February 1976, while food selection was analyzed using larvae and zooplankton samples collected in February 1982. Hatching occurs in early spring, and larvae fed on eggs of calanoid copepods and on cyclopoid copepods. Copepod eggs were the principal food near the pack ice, and cyclopoids in open waters. Cyclopoids were the staple food in summer. Eggs of the Antarctic krillEuphausia superba were ingested selectively and formed major portions of the larval summer diet in neritic (Joinville Island) and oceanic (Elephant Island) spawning areas ofE. superba. In the fall, copepods predominated in the diets. Most abundant and most frequently ingested prey in summer and fall wereOncaea spp. Feeding commenced at dawn and continued at least until dusk. Krill eggs were taken chiefly during morning hours and egg incidence declined during the day, suggesting that eggs were ingested soon after spawning. Prey size at the onset of feeding was estimated as 0.130 to 0.330 mm. Size-selective feeding was evident in small larvae, while in larger larvae median prey length remained constant. High feeding incidence among yolk-sac larvae in spring, high overall feeding incidence in summer, and size-selective foraging of small larvae suggested favorable feeding conditions in the 1977/1978 season. Yolk-absorption times in Antarctic fish larvae vary on a scale of weeks and may be further retarded due to early feeding. Hence, year-to-year variability of yolk incidence inN. larseni indicated variable biotic environments of early feeding larvae rather than temporal shifts of hatching periods. As hatching periods are constant between years in contrast to the variable retreat of the pack ice and subsequent onset of the production cycle in space and time, maternal yolk reserves are probably utilized to compensate for such variations. 相似文献
6.
Larval fish growth and survival depends not only on prey quantity, but also on prey quality. To investigate effects of prey fatty acid concentration on larval herring growth, we collected different prey organisms and larval herring (Clupea harengus L.) in the Kiel Canal during the spring season of 2009. Along with biotic background data, we analysed fatty acids both in prey organisms and in the larvae and used biochemically derived growth rates of the larvae as the response variable. Larval herring reached their highest RNA/DNA derived growth rates only at high docosahexaenoic acid (DHA) concentration. When the ratio of copepodids to lesser quality cirriped nauplii was low, larval growth and larval DHA concentration were both significantly negatively affected. This was true even as prey abundance was increasing. This finding indicates that even in mixed, natural feeding conditions, growth variations are associated with DHA availability in larval fish. 相似文献
7.
The zoeal larvae of brachyuran crabs must feed soon after hatching on a diet that includes large micro- and mesozooplankton
in order to satisfy nutritional requirements. However, newly hatched larvae have been shown to ingest a variety of dinoflagellates,
perhaps using microbial carbon sources to sustain them until they encounter more favored prey. Ingestion of dinoflagellates
by larval crabs has been documented previously under conditions in which the larvae were exposed to algae provided in monoculture
or in defined mixtures of cells. We report here on experiments conducted on the hatching stage of five crab species to determine
if ingestion of dinoflagellates occurred when they were provided in combination with Artemia sp. nauplii or after a period of feeding on mesozooplankton. Quantitative measurements of chl a in the larval guts provided evidence of ingestion of algal cells. Active ingestion of the dinoflagellate Prorocentrum micans at specified intervals during an extended feeding period was determined on larvae of two crab species using fluorescently
labeled cells provided for brief periods at prescribed time intervals. Stage 1 larvae of four of the five crab species ingested
dinoflagellates when they were provided in combination with nauplii and larvae of all five species ingested cells after feeding
solely on nauplii for 24 h. Ingestion of algal cells was first evident in the larval guts after 6 h of feeding at both low
(200 cell ml−1) and high (1,000 cells ml−1) prey densities. Higher prey densities resulted in higher gut chl a. Larvae continuously exposed to dinoflagellates actively ingested cells at every 3 h interval tested over a 36 h period.
Results confirm previous studies that larvae will ingest dinoflagellates even when they are encountered in a mixed prey field
or when having previously fed. Ingestion of cells may occur on a continual basis over time. 相似文献
8.
Britta Grote Wilhelm Hagen Marek R. Lipinski Hans M. Verheye Erling K. Stenevik Werner Ekau 《Marine Biology》2011,158(5):1005-1017
Cape hakes, Merluccius paradoxus and M. capensis, are important gadoid fish that are commercially harvested in the Benguela Current system off Namibia and South Africa. The
aim of this study was to elucidate the nutritional condition and feeding preferences of their larvae. Hake eggs and larvae
were sampled in austral spring of two consecutive years, 2007 and 2008, off the west coast of South Africa. They were identified
to species using genetics, and total lipid content and fatty acid (FA) composition were analysed for each individual egg and
larva to compare the condition of different early life stages of both hake species. Higher abundances of M. paradoxus eggs and larvae were consistently found compared to M. capensis. In both species, eggs contained wax esters (WE) and had significantly higher lipid content per dry mass than larvae. Lipid
content as well as FA composition changed with the developmental stage of larvae. Quantities of essential fatty acid (EFA)
increased with feeding of larvae due to dietary lipid incorporation. In 2007, yolk-sac larvae contained significantly lower
total lipids than in 2008. It is argued that this was due to reduced lipid transfer by the spawning females to the eggs. These
findings indicate that maternal effects are important in determining condition of hake larvae and that this may have an effect
on their survival and subsequent recruitment. 相似文献
9.
Trypsin and its proform trypsinogen were quantified by radioimmunoassay in herring (Clupea harengus L.) larvae subjected to different prey densities. During the first weeks of larval life, the enzyme content fluctuated in a threephased pattern. Yolk resorption (Phase 1) was characterized by an increase in enzyme. During the first few days after yolk resorption (Phase 2), there was a sharp decline in enzyme. Older larvae (Phase 3) exhibited a second period of intensive enzyme synthesis. Amounts of trypsin in intestines of feeding larvae were analysed. At first feeding, a basal level of gut enzyme of approximately 30ng was recorded, and the amount of additional enzyme secreted from the pancreatic tissue into the intestine appeared to be dependent upon the numbers of prey items ingested. The enzyme-substrate ratio in the intestine was approximately 1 to 4. Prey availability affected amount of trypsinogen. Larvae experiencing a high prey density had an approximately two-fold higher specific enzyme content in Phase 2 compared to larvae exposed to a low prey density. A proposed nutritional strategy for first feeding herring larvae is discussed. 相似文献
10.
Patricia N. Pochelon Henrique Queiroga Guiomar Rotllant Antonina dos Santos Ricardo Calado 《Marine Biology》2011,158(9):2079-2085
In Portuguese waters, Nephrops norvegicus larvae hatch at 400–800 m depth and need to perform a vertical migration to food-rich shallower waters to find suitable prey.
The effect of suboptimal feeding on digestive enzymes activity of N. norvegicus larvae during this early period of their larval life remains unknown. Protease and amylase activities were investigated ex situ using flurometry in laboratory-hatched larvae exposed to different feeding and/or starving scenarios in the 24 h following
hatching, the period during which they typically accomplish their upward vertical migration. Amylase activity was very low
in comparison with protease activity, indicating that carbohydrates are not a primary energy reserve. Larvae starved for 12 h
and subsequently fed displayed no increase in amylase activity, which suggests that feeding may be required before 12 h post-hatch
to trigger amylase activity. Protease activity was high under all feeding conditions, and the increase in protease activity
under sustained starvation indicated the catabolism of protein reserves. The ability of first-stage N. norvegicus larvae to metabolize protein reserves may play a decisive role for their survival during their first vertical migration,
as it enables them to overcome the deleterious effects of short-term starvation and/or suboptimal feeding. 相似文献
11.
Prey selection by larval weakfish (Cynoscion regalis): the effects of prey size,speed, and abundance
We examined feeding by larval weakfish, Cynoscion regalis (Bloch and Schneider), in laboratory experiments conducted during the 1991 spawning season. under natural conditions weakfish larval development is ca. 3 wk, and we ran separate experiments with larvae of five different ages (5, 8, 11, 14, and 17 d post-hatching). We used two different size classes of rotifers (Brachionus plicatilis) and brine shrimp nauplii (Artemia sp.) as prey organisms. Contrary to results of previous research, weakfish larvae did not select prey based on size alone. When prey abundance was above 100 itemsl-1 weakfish, larvae always chose large rotifers (length = 216 m) over small rotifers (length = 160 m). At 11 d post-hatching, larvae switched their diet from large rotifers to small brine shrimp nauplii (length = 449 m); however, when fed small rotifers and small brine shrimp nauplii the change in diet occurred at 14 d post-hatching. This pattern of selectivity was maintained in each larval age class. Early-stage larvae (5 and 8 d post-hatching) did not feed selectively when prey abundance was less than 100 itemsl-1. Late-stage larvae (17 d post-hatching) fed selectively at abundances ranging from 10 to 10000 items-1. Lwimming speeds of prey items, which ranged from 1 to 6 mms-1, had no consistent effect on prey selection. These results suggest that weakfish larvae are able to feed selectively, that selectivity changes as larvae age, and that selectivity is also influenced by prey abundance. 相似文献
12.
Most marine fishes undergo a pelagic larval phase, the early life history stage that is often associated with a high rate
of mortality due to starvation and predation. We present the first study that examines the effects of prey swimming behavior
on prey-capture kinematics in marine fish larvae. Using a digital high-speed video camera, we recorded the swimming velocity
of zooplankton prey (Artemia franciscana, Brachionus rotundiformis, a ciliate species, and two species of copepods) and the feeding behavior of red drum (Sciaenops ocellatus) larvae. From the video recordings we measured: (1) zooplankton swimming velocity in the absence of a red drum larva; (2)
zooplankton swimming velocity in the presence of a red drum larva; and (3) the excursion and timing of key kinematic events
during prey capture in red drum larvae. Two-way ANOVA revealed that: (1) swimming velocity varied among zooplankton prey;
and (2) all zooplankton prey, except rotifers and ciliates, increased their swimming velocity in the presence of a red drum
larva. The kinematics of prey capture differed between two developmental stages in S. ocellatus larvae. Hyoid-stage larvae (3–14 days old) fed on slow swimming B. rotundiformis (rotifers) while hyoid-opercular stage larvae (15 days and older) ate fast moving A. franciscana. Hyoid-opercular stage red drum larvae had a larger gape, hyoid depression and lower jaw angle, and a longer gape cycle duration
relative to their hyoid-stage conspecifics. Interestingly, the feeding repertoire within either stage of red drum development
was not affected by prey type. Knowledge of the direct relationship between fish larvae and their prey aids in our understanding
of optimal foraging strategies and of the sources of mortality in marine fish larvae. 相似文献
13.
Food limitation is likely to be a source of mortality for fish larvae in the first few weeks after hatching. In the laboratory,
we analyzed all aspects of foraging in cod larvae (Gadus morhua Linnaeus) from 5 to 20 d post-hatching using protozoa (Balanion sp.) and copepod nauplii (Pseudodiaptomus sp.) as prey. A camera acquisition system with two orthogonal cameras and a digital image analysis program was used to observe
patterns of foraging. Digitization provided three-dimensional speeds, distances, and angles for each foraging event, and determined
prey and fish larval head and tail positions. Larval cod swimming speeds, perception distances, angles, and volumes increased
with larval fish size. Larval cod swam in a series of short intense bursts interspersed with slower gliding sequences. In
94% of all foraging events prey items were perceived during glides. Larval cod foraging has three possible outcomes: unsuccessful
attacks, aborted attacks, and successful attacks. The percentage of successful attacks increased with fish size. In all larval
fish size classes, successful attacks had smaller attack distances and faster attack speeds than unsuccessful attacks. Among
prey items slowly swimming protozoans were the preferred food of first-feeding cod larvae; larger larvae had higher swimming
speeds and captured larger, faster copepod nauplii. Protozoans may be an important prey item for first-feeding larvae providing
essential resources for growth to a size at which copepod nauplii are captured.
Received: 20 April 1999 / Accepted: 12 January 2000 相似文献
14.
Tomohiro Kuwae 《Marine Biology》2007,151(2):803-804
To elucidate the effects of light, site, temperature, time after emersion, and wind speed on foraging attempt rate (FAR) (attempts/unit
time) and feeding success (FS) (captures/attempts) in the obligate visual foraging shorebird, Kentish plovers Charadrius alexandrinus, field observations were performed at a sandflat in Tokyo Bay, using a visible-light telescope camcorder during the day and
a thermal infrared telescope camcorder at night. The re-analysis capability and frame-step replay of highly magnified video-images
can contribute to accurate measurement of feeding behaviour over conventional focal observation techniques. Kentish plovers
increased both FAR and FS in areas of high prey (polychaetes and crabs) density, resulting in a synergistic increase in feeding
rate (captures/unit time). In areas of high prey abundance, FAR was higher at lower wind speed. FS increased with increasing
time after emersion. Increasing temperatures induced a positive effect on FAR but a negative effect on FS. The effect of light
on FAR was not observed; however, time-to-defecation occurrence was 2.2-fold shorter at night than during the day, indicating
that feeding rate and FS are higher at night. These results are attributable to an increase in availability of cues due to
higher nocturnal activity in polychaetes. Since available foraging time (emersion time) at night was 1.7-fold longer than
during the day in the present study period, Kentish plovers could capture 3.7-fold (2.2 × 1.7) more prey at night than during
the day. Results from this study indicate that nocturnal feeding in overwintering plovers is not a compensation but a major
foraging activity to meet their energy requirements.
An erratum to this article can be found at 相似文献
15.
Food selection by young larvae of the gulf menhaden (Brevoortia patronus) was studied in the laboratory at Beaufort, North Carolina (USA) in 1982 and 1983; this species is especially interesting, since the larvae began feeding on phytoplankton as well as microzooplankton. When dinoflagellates (Prorocentrum micans), tintinnids (Favella sp.), and N1 nauplii of a copepod (Acartia tonsa) were presented to laboratory-reared, larval menhaden (3.9 to 4.2 mm notochord length), the fish larvae ate dinoflagellates and tintinnids, but not copepod nauplii. Larvae showed significant (P<0.001) selection for the tintinnids. Given the same mixture of food items, larger larvae (6.4 mm notochord length) ate copepod nauplii as well as the other food organisms. These feeding responses are consistent with larval feeding in the northern Gulf of Mexico, where gulf menhaden larvae between 3 and 5 mm in notochord length frequently ate large numbers of dinoflagellates (mostly P. micans and P. compressum) and tintinnids (mostly Favella sp.), but did not eat copepod nauplii. As larvae grew, copepod nauplii and other food organisms became important, while dinoflagellates and tintinnids became relatively less important in the diet. Since the tintinnids and nauplii used in the laboratory feeding experiments were similar in size as well as carbon and nitrogen contents, the feeding selectivity and dietary ontogeny that we observed were likely due to a combination of prey capturability and larval fish maturation and learning.Contribution No. 5575 of the Woods Hole Oceanographic Institution 相似文献
16.
Investigations of factors affecting feeding success in fish larvae require knowledge of the scales of variability of the
feeding process itself and the indices used to assess this variability. In this study, we measured short-term (diel) variability
in feeding rates of wild haddock (Melanogrammus aeglifinus) larvae four times per day during a 10-d cruise in the northern North Sea. Feeding activity was evaluated using indices of
gut fullness, prey digestive state and biochemical measurements (tryptic enzyme activity). The gut fullness and the enzyme
activity indices indicated moderate to high rates of food consumption throughout the cruise. Time series analysis of the three
indices showed significant diel variability in all indices and enabled identification of significant lags between food uptake
and peak digestive enzyme activity. The typical pattern of food consumption and digestion was characterized by maximal ingestion
of prey early in the evening (19:00 hrs) and peak digestive enzyme activity at 01:00 hrs. The time scale over which enzyme
activities reacted to prey ingestion was ca. 6 h, and is consistent with expectations from controlled laboratory experiments
with other larval fish species. Significant diel variability in tryptic enzyme activity suggests that attempts to relate this
measure of feeding success to other variables (e.g. food concentrations) should take care to accommodate natural cycles in
feeding activity before making statistical comparisons.
Received: 29 October 1998 / Accepted: 18 June 1999 相似文献
17.
Feeding rates of the jellyfish Aurelia aurita on fish larvae 总被引:4,自引:0,他引:4
We quantified feeding rates of field caught Aurelia aurita feeding on yolk sac cod (Gadus morhua) larvae in a series of incubation experiments. A short-time (~1 h) functional response experiment with a wide range of prey concentrations (0.5–16 prey l−1, initial concentration) revealed that ingestion rates increased linearly over this range, such that clearance rates were similar between the different prey concentrations. This suggests that A. aurita is capable of efficiently utilizing dense prey patches. This indication was further supported by a linear increase of prey captured by A. aurita during 2.5 h of feeding at extremely high prey concentration (>200 prey l−1). Clearance rate in darkness scaled with jellyfish diameter to a power of ~1.7 for jellyfish 3.9–9.5 cm in diameter. The jellyfish did not alter their umbrella pulse frequency in response to presence of fish larvae. There were no significant differences between A. aurita feeding rates in light and darkness for yolk sac prey ages 0–7 days (at 7.5°C). Although prey vision and escape abilities of fish may develop rapidly during early larval ontogeny, these factors apparently have little impact on interactions with predators such as A. aurita during the yolk sac stage. 相似文献
18.
Summary. Detection of heterospecific predators and prey
via chemical cues is well known, but only a few studies have
examined the potential for such discrimination in cannibalistic
systems. In newts, Notophthalmus viridescens, adults are
opportunistic predators of conspecific larvae. I used a laboratory
bioassay to determine whether larvae and adults distinguish
between chemical stimuli from members of the
different age classes. Larvae distinguished between chemical
stimuli from larvae and adults by decreasing their activity
only following exposure to stimuli from adults. Decreased
activity is consistent with an antipredator response in many
prey species, including larval newts. In contrast, adults
increased their activity and increased time spent in open
areas in response to stimuli from larvae, but not to stimuli
from adults. Increased activity is consistent with a feeding
response; adults also showed increased activity and
increased time in open areas in response to chemical stimuli
from familiar heterospecific prey (brine shrimp). The proximate
cue that allowed the newts to distinguish between the
different age classes is not associated with short-term
dietary differences because all stimulus animals were fed the
same prey. Stimulus strength was controlled by diluting the
stimulus solutions according to the volume of the stimulus
animal. Therefore, there appear to be intrinsic differences in
the chemical signatures of larval and adult newts. 相似文献
19.
Extent of larval growth among marine invertebrates has potentially profound implications for performance by benthic recruits
because body size influences many biological processes. Among gastropods, feeding larvae often attain larger size at metamorphic
competence than non-feeding larvae of basal gastropod clades. Delay of metamorphosis can further influence size at recruitment
if larvae continue to grow during the delay. Some caenogastopod larvae grow during delayed metamorphosis, but opisthobranch
larvae do not. Data on larval growth of neritimorph gastropods are needed to help determine which of these growth patterns
for planktotrophic gastropod larvae is more derived. We cultured planktotrophic larvae from all three major gastropod clades
with feeding larvae through delays of metamorphosis of 3–10 weeks. Larvae of the caenogastropod Euspira lewisii and the euthyneurans Haminoea vesicula (Opisthobranchia) and Siphonaria denticulata (Pulmonata) conformed to previously described growth patterns for their respective major clades. Furthermore, the caenogastropod
continued to lengthen the prototroch (ciliary band for swimming and feeding) and to differentiate prospective post-metamorphic
structures (gill filaments and radular teeth) during delayed metamorphosis. Larvae of the neritimorph Nerita atramentosa arrested shell growth during delayed metamorphosis but the radula continued to elongate, a pattern most similar to that of
non-feeding larvae of Haliotis, a vetigastropod genus. Character mapping on a phylogenetic hypothesis suggests that large larval size and capacity for continued
growth during delayed metamorphosis, as exhibited by some caenogastropods, is a derived innovation among feeding gastropod
larvae. This novelty may have facilitated post-metamorphic evolution of predatory feeding using a long proboscis. 相似文献
20.
D. F. Malley 《Marine Biology》1978,48(4):377-386
The food and feeding habits of 3 species of gadoid larvae — the cod Gadus morhua Linnaeus, 1758, the whiting Merlangius merlangus (Linnaeus, 1758), and the bib Trisopterus luscus (Linnaeus, 1758), collected in the eastern English Channel and Southern Bight during the spring of 1971 are described. All 3 species began to feed in the yolk-sac stage on diatoms, dinoflagellates and tintinnids, but the principal food was the nauplii and copepodites of calanoid copepods, particularly of Pseudocalanus minutes, but also of Paracalanus parvus, Temora longicornis and Acartia clausii. Pseudocalanus minutus and Paracalanus parvus were eaten mainly early in the season and T. longicornis later when it became more abundant. The larvae discriminated for prey size as growth proceeded. They sometimes took the largest prey available to them, but in general the size of the prey was considerably less than the maximum size which could have been swallowed. Feeding larvae were found at all times of the day, but the incidence of feeding was lowest before dawn. Feeding increased at sunrise, declined until late in the morning, and then increased again to a maximum around sunset. There was evidence of feeding by moonlight, particularly by whiting and bib larvae. There was little difference between the English Channel and Southern Bight in regard to the food eaten. 相似文献