A lopsided face helps this eyeless cave fish navigate

first_img Sign up for our daily newsletter Get more great content like this delivered right to you! Country Click to view the privacy policy. Required fields are indicated by an asterisk (*) To discover the genetic basis for the difference, they then bred the surface fish with the cave fish; those descendants with extra neuromasts tended to have a higher expression of a gene called Mn1. In mice, defective Mn1 leads to abnormal facial bones. In the fish, the extra neuromasts usually show up where bones have grown cock-eyed, leading the scientists to think neuromasts may somehow cause developing bone to misform.That could have implications for fish, mice, and even humans, who are affected by 700 so-called “craniofacial” syndromes. As the researchers continue to investigate the connection between neuromasts, bone asymmetry, and behavior, they hope to clarify how developing sensory and skeletal tissues interact to cause irregularities in the skull—some of them more useful than others. Next, the researchers counted mechanical sensors known as neuromasts in the heads of embryonic fish. These sensors, or “nerve buttons,” detect water flow and sometimes vibrations. Blind fish had more—and larger—neuromasts than fish of the same species that lived on the surface, they reported. Amanda Powers and Josh Gross Country * Afghanistan Aland Islands Albania Algeria Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia, Plurinational State of Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Indian Ocean Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, the Democratic Republic of the Cook Islands Costa Rica Cote d’Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands (Malvinas) Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City State) Honduras Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea, Democratic People’s Republic of Korea, Republic of Kuwait Kyrgyzstan Lao People’s Democratic Republic Latvia Lebanon Lesotho Liberia Libyan Arab Jamahiriya Liechtenstein Lithuania Luxembourg Macao Macedonia, the former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Martinique Mauritania Mauritius Mayotte Mexico Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Norway Oman Pakistan Palestine Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Qatar Reunion Romania Russian Federation Rwanda Saint Barthélemy Saint Helena, Ascension and Tristan da Cunha Saint Kitts and Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan Suriname Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Uruguay Uzbekistan Vanuatu Venezuela, Bolivarian Republic of Vietnam Virgin Islands, British Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe TAMPA, FLORIDA—The pinnacle of beauty to most people is a symmetrical face, one without any major left-right differences. But for blind Mexican cavefish (Astyanax mexicanus), asymmetry may be a lifesaver. That’s because their lopsided skulls may help them feel their way along dark cave walls—similar to a person navigating by touch in the dark. That behavior, presented here this week at the annual meeting of the Society for Integrative and Comparative Biology, suggests being a little “off” can have evolutionary benefits.Lots of cave dwellers are a bit unbalanced. Cave fish tend to have one eye that is larger than the other, for example, and cave crickets have different size antennae. Some researchers wondered whether left-right differences might help these creatures get around.They scanned the skulls of A. mexicanus fish from three caves in Mexico. Their computerized tomography scans revealed most fish skulls bent slightly to the left, giving the right side of their faces slightly more exposure. Other tests showed these fish tended to drift along the right-hand side of cave walls, presumably using the larger side of their faces to feel their way in the dark. Email By Elizabeth PennisiJan. 4, 2019 , 8:45 AM Daniel Berning and Josh Gross A lopsided face helps this eyeless cave fish navigatelast_img read more

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