Nutrient and energy consumption of captive mature dugong (Dugong dugon) consuming eelgrass at the Toba Aquarium

Goto, Masakazu; Watanabe, Asako; Karita, Shuichi; Tokita, Norio; Yamamoto, Yasunari; Wakaki, Yoshihito; Asano, Shiro; Oka, Yukari; Furuta, Masami

doi:10.1080/10236240802284445

Cited by 5 publications

(6 citation statements)

References 27 publications

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“…The extremely low metabolic rates of manatees and sloths are expected to lower cancer rates [9]. A similar effect would apply to dugongs, anteaters and hyraxes as these also have low metabolic rates, albeit not as extreme as in sloths and manatees [133-136] and, hence, they may also have reduced cancer rates.…”

Section: Discussionmentioning

confidence: 99%

Breaking evolutionary and pleiotropic constraints in mammals: On sloths, manatees and homeotic mutations

Varela-Lasheras

Bakker

Mije

et al. 2011

EvoDevo

119

143

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BackgroundMammals as a rule have seven cervical vertebrae, except for sloths and manatees. Bateson proposed that the change in the number of cervical vertebrae in sloths is due to homeotic transformations. A recent hypothesis proposes that the number of cervical vertebrae in sloths is unchanged and that instead the derived pattern is due to abnormal primaxial/abaxial patterning.ResultsWe test the detailed predictions derived from both hypotheses for the skeletal patterns in sloths and manatees for both hypotheses. We find strong support for Bateson's homeosis hypothesis. The observed vertebral and rib patterns cannot be explained by changes in primaxial/abaxial patterning. Vertebral patterns in sloths and manatees are similar to those in mice and humans with abnormal numbers of cervical vertebrae: incomplete and asymmetric homeotic transformations are common and associated with skeletal abnormalities. In sloths the homeotic vertebral shift involves a large part of the vertebral column. As such, similarity is greatest with mice mutant for genes upstream of Hox.ConclusionsWe found no skeletal abnormalities in specimens of sister taxa with a normal number of cervical vertebrae. However, we always found such abnormalities in conspecifics with an abnormal number, as in many of the investigated dugongs. These findings strongly support the hypothesis that the evolutionary constraints on changes of the number of cervical vertebrae in mammals is due to deleterious pleitropic effects. We hypothesize that in sloths and manatees low metabolic and activity rates severely reduce the usual stabilizing selection, allowing the breaking of the pleiotropic constraints. This probably also applies to dugongs, although to a lesser extent.

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Section: Discussionmentioning

confidence: 99%

Breaking evolutionary and pleiotropic constraints in mammals: On sloths, manatees and homeotic mutations

Varela-Lasheras

Bakker

Mije

et al. 2011

EvoDevo

119

143

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“…Drastic dietary changes have been shown to result in modification of the gut flora in other mammalian species (e.g., Rowland et al 1985;Juliand 2005), and the sudden change in diet that our ex situ manatees experienced when they were switched to a seagrass diet could account for the difference in D m seen between them and in situ animals in the marine environment. Our data also indicate that manatees consuming seagrasses differ significantly in their D m from dugongs on a seagrass diet (Murray et al 1977;Aketa et al 2001Aketa et al , 2003Goto et al 2004Goto et al , 2008.…”

Section: Discussionmentioning

confidence: 64%

“…Different species of seagrasses can vary dramatically in their digestibility, with dugongs having a D m of up to 85% when consuming seagrass (Aketa et al 2001(Aketa et al , 2003Goto et al 2008). Several authors have suggested that dugongs must consume plant species that are highly digestible (Halophila) and have high nutrient contents (Halodule) to maximize nutrient intake (Preen 1992;Lanyon and March 1995;Aragones 1996;Aragones and Marsh 2000;Lanyon and Sanson 2006).…”

Section: Discussionmentioning

confidence: 98%

Digestive Efficiencies of Ex Situ and In Situ West Indian Manatees (Trichechus manatus latirostris)

Worthy

2014

Physiological and Biochemical Zoology

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Digestive efficiencies (Dm) of ex situ and in situ manatees (Trichechus manatus latirostris) were, for the first time, assessed using manganese (Mn(2+)) as a naturally occurring marker. The Dm of ex situ manatees determined using [Mn(2+)] did not differ significantly from the Dm assessed using lignin, supporting the efficacy of the manganese approach. Gastrointestinal tract samples, obtained from recently dead animals, showed [Mn(2+)] concentrations were lowest in the stomach and remained low in the duodenum and small intestine but increased in the cecum, colon, and rectum, consistent with colonic digestion and absorption. In situ manatees consuming marine vegetation had significantly lower Dm (mean ± SE, 46.9% ± 1.8%; n=8) than did in situ manatees consuming freshwater vegetation (77.8% ± 2.6%; n=7), which in turn had significantly lower values than did ex situ manatees consuming lettuce (84.0% ± 0.7%; n=37). In situ manatees eating seagrasses had significantly higher Dm than did long-term ex situ animals consuming seagrass for short periods of time (46.9% ± 1.8% vs. 36.2% ± 1.2%, respectively), suggesting potential modification of gut flora over time. One significant ramification of our results is that manatees consuming seagrasses would require a greater standing biomass to support their needs than would be required if they were eating freshwater vegetation. This reinforces the critical need to implement habitat conservation and protection before considering downlisting or delisting manatees as an endangered species.

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“…These could be linked to a low basal metabolic rate (BMR). Afrotherian taxa have relatively low BMRs compared to other placental mammals [McNairn and Fairall, 1984;O'Shea and Reep, 1990;Milner and Harris, 1999;Goto et al, 2008], a trend also seen in xenarthran taxa [Fowler and Cubas, 2001;Vizcaíno and Loughry, 2008]. These taxa also have lower BMR scaling than most other placental mammals; therefore, as their body mass increases, their BMR increases at a relatively low rate [White et al, 2009].…”

Section: Possible Factors Influencing Manatee Neuron Types and Distrimentioning

confidence: 97%

“…These taxa also have lower BMR scaling than most other placental mammals; therefore, as their body mass increases, their BMR increases at a relatively low rate [White et al, 2009]. Even compared to dugongs and other aquatic mammals, manatees have a low BMR [Gallivan and Best, 1980;Irvine, 1983;Goto et al, 2008;Varela-Lasheras et al, 2011], and there is evidence that a low BMR can affect a variety of systems in the body.…”

Section: Possible Factors Influencing Manatee Neuron Types and Distrimentioning

confidence: 99%

Neuron Types in the Presumptive Primary Somatosensory Cortex of the Florida Manatee (Trichechus manatus latirostris)

Reyes

Stimpson²,

Gupta³

et al. 2015

Brain Behav Evol

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Within afrotherians, sirenians are unusual due to their aquatic lifestyle, large body size and relatively large lissencephalic brain. However, little is known about the neuron type distributions of the cerebral cortex in sirenians within the context of other afrotherians and aquatic mammals. The present study investigated two cortical regions, dorsolateral cortex area 1 (DL1) and cluster cortex area 2 (CL2), in the presumptive primary somatosensory cortex (S1) in Florida manatees (Trichechus manatus latirostris) to characterize cyto- and chemoarchitecture. The mean neuron density for both cortical regions was 35,617 neurons/mm³ and fell within the 95% prediction intervals relative to brain mass based on a reference group of afrotherians and xenarthrans. Densities of inhibitory interneuron subtypes labeled against calcium-binding proteins and neuropeptide Y were relatively low compared to afrotherians and xenarthrans and also formed a small percentage of the overall population of inhibitory interneurons as revealed by GAD67 immunoreactivity. Nonphosphorylated neurofilament protein-immunoreactive (NPNFP-ir) neurons comprised a mean of 60% of neurons in layer V across DL1 and CL2. DL1 contained a higher percentage of NPNFP-ir neurons than CL2, although CL2 had a higher variety of morphological types. The mean percentage of NPNFP-ir neurons in the two regions of the presumptive S1 were low compared to other afrotherians and xenarthrans but were within the 95% prediction intervals relative to brain mass, and their morphologies were comparable to those found in other afrotherians and xenarthrans. Although this specific pattern of neuron types and densities sets the manatee apart from other afrotherians and xenarthrans, the manatee isocortex does not appear to be explicitly adapted for an aquatic habitat. Many of the features that are shared between manatees and cetaceans are also shared with a diverse array of terrestrial mammals and likely represent highly conserved neural features. A comparative study across manatees and dugongs is necessary to determine whether these traits are specific to one or more of the manatee species, or can be generalized to all sirenians.

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Nutrient and energy consumption of captive mature dugong (Dugong dugon) consuming eelgrass at the Toba Aquarium

Cited by 5 publications

References 27 publications

Breaking evolutionary and pleiotropic constraints in mammals: On sloths, manatees and homeotic mutations

Breaking evolutionary and pleiotropic constraints in mammals: On sloths, manatees and homeotic mutations

Digestive Efficiencies of Ex Situ and In Situ West Indian Manatees (Trichechus manatus latirostris)

Neuron Types in the Presumptive Primary Somatosensory Cortex of the Florida Manatee <b><i>(Trichechus manatus latirostris)</i></b>

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