據(jù)7月24日的《科學(xué)》雜志報(bào)道說(shuō)，一項(xiàng)新的研究提示,，如同大象的耳朵一樣,，巨嘴鳥(niǎo)的喙可像一個(gè)相當(dāng)有效的散熱器一樣運(yùn)作，即在該鳥(niǎo)需要降低體溫的時(shí)候?qū)⑸眢w的熱量排放出去,。
托哥巨嘴鳥(niǎo)（toco toucan ）的喙在動(dòng)物奇觀堂中占有一席特殊的位置,。 該鳥(niǎo)的喙占了其整個(gè)身長(zhǎng)的約1/3，相對(duì)于其身體大小來(lái)說(shuō),，它的喙是所有鳥(niǎo)中最大的,。 研究人員在幾個(gè)世紀(jì)以來(lái)一直對(duì)該鳥(niǎo)喙的功能感到困惑，有人提出,，其功用可能與吸引配偶或處理果實(shí)有關(guān),。 Glenn Tattersall及其同僚對(duì)一種替代性的解釋進(jìn)行了調(diào)查。他們用紅外熱成像（即熱感應(yīng)攝相機(jī)）來(lái)監(jiān)視接觸不同環(huán)境溫度時(shí)的巨嘴鳥(niǎo),。 研究人員觀察到,，該鳥(niǎo)喙的表面溫度在其環(huán)境變熱或變冷時(shí)會(huì)快速地改變。 例如,，在日落的時(shí)候,，當(dāng)巨嘴鳥(niǎo)即將入眠的時(shí)候，其鳥(niǎo)喙會(huì)在幾分鐘內(nèi)降溫約10攝氏度,。 這種鳥(niǎo)因此看來(lái)是在用它們的喙（該鳥(niǎo)喙上有許多血管,，可使其體熱被攜往該鳥(niǎo)喙的表面附近）來(lái)散發(fā)體熱，這樣,，它們可以在睡眠的時(shí)候降低其體溫,。 文章的作者猜測(cè)，其它的鳥(niǎo)類（由于無(wú)法出汗）可能也是用它們的喙來(lái)達(dá)到這一目的的,。（生物谷Bioon.com）
生物谷推薦原始出處：
Science 24 July 2009: DOI: 10.1126/science.1175553
Heat Exchange from the Toucan Bill Reveals a Controllable Vascular Thermal Radiator
Glenn J. Tattersall,1,3 Denis V. Andrade,2,3 Augusto S. Abe2,3
The toco toucan (Ramphastos toco), the largest member of the toucan family, possesses the largest beak relative to body size of all birds. This exaggerated feature has received various interpretations, from serving as a sexual ornament to being a refined adaptation for feeding. However, it is also a significant surface area for heat exchange. Here we show the remarkable capacity of the toco toucan to regulate heat distribution by modifying blood flow, using the bill as a transient thermal radiator. Our results indicate that the toucan's bill is, relative to its size, one of the largest thermal windows in the animal kingdom, rivaling elephants’ ears in its ability to radiate body heat.
1 Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada.
2 Departamento de Zoologia, Universidade Estadual Paulista, Campus Rio Claro, S?o Paulo, Brazil.
3 Instituto Nacional de Ciência e Tecnologia em Fisiologia Comparada.
