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<DIV class=instapaper_title><FONT size=4>Whales tan too, basking in the big
blue</FONT></DIV>
<DIV>by <A href="http://www.newscientist.com/search?rbauthors=Andy+Coghlan"
s_oc="null"><FONT color=#000000>Andy Coghlan</FONT></A></DIV>
<DIV>30 August 2013 </DIV>
<DIV><A
href="http://www.newscientist.com/article/dn24133?cmpid=NLC%7CNSNS%7C2013-0509-GLOBAL&utm_medium=NLC&utm_source=NSNS">http://www.newscientist.com/article/dn24133?cmpid=NLC%7CNSNS%7C2013-0509-GLOBAL&utm_medium=NLC&utm_source=NSNS</A>&</DIV><!-- pgtop -->
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<P class=infuse>Whales tan too. Just like us, they do it to protect themselves
from powerful ultraviolet radiation.</P>
<P class=infuse>A study of skin samples taken from blue, fin and sperm whales in
Mexico's Gulf of California found that the blue whales show the most obvious
tanning effects. Samples were collected between January and June from 2007 to
2009.</P>
<P class=infuse>Blue whales migrate annually between the Arctic and the Gulf of
California. The team, led by <A
href="http://www.ncl.ac.uk/biomedicine/research/groups/profile/mark.birch-machin"
s_oc="null">Mark Birch-Machin</A> of Newcastle University, UK, found that their
grey skins darken with melanin as ultraviolet radiation intensifies from
February to May in the Gulf.</P>
<P class=infuse>Birch-Machin and his colleagues also found that damage to
mitochondrial DNA in skin cells dropped as the whales' skin darkened,
demonstrating that melanin protects them against UV-induced DNA damage, just as
it does in humans.</P>
<H3 class=crosshead><FONT size=2>Perma-tanned</FONT></H3>
<P class=infuse>But neither fin nor sperm whales appeared to change colour
noticeably. Unlike blue whales, which migrate annually between the Arctic and
Mexico, fin whales live in the Gulf of California all year round, and so are
permanently exposed to high UV levels. They had the darkest skin with the
highest melanin content.</P>
<P class=infuse>Sperm whales spend long periods at the sea surface. For
sun-factor protection, they rely on melanin and a substance called heat-shock
protein 70, which repairs proteins damaged by UV light. "The amount of UV
they're exposed to would overwhelm pigments alone," says Birch-Machin.</P>
<P class=infuse>He says the results are the first to show from analysis of DNA
and skin that animals rely on pigments too for sun protection. Karina
Acevedo-Whitehouse of the Zoological Society of London, <A
href="http://www.newscientist.com/article/dn19707-californias-whales-suffer-sunburn.html"
s_oc="null">reported the first sighting of sunburnt whales three years ago </A>.
Birch-Machin says that whether sunburn leads to melanomas in whales – as has
been documented in trout – is not known.</P>
<P class=infuse>Journal reference: <I>Nature Scientific Reports</I>, DOI: <A
href="http://doi.org/nnq"
s_oc="null">10.1038/srep02386</A></P></DIV></DIV></DIV></FONT></BODY></HTML>