BIOLOGY [ES] * HEALTH [ES]
Objectives
After viewing the video and participating in one or more of the Hands-On Activities, students will be able to:
• describe physiological adaptations at a cellular level (e.g. red blood cells and hemoglobin) which allow Antarctic seals to hold their breath enough to dive deep and long
• understand that since mammals share certain similar body systems, it may be possible to learn about human physiology through comparisons (e.g. SIDS)
• discuss the fact that the behavior of a mature Weddell seal is the result both of biology and learning, nature and nurture
• describe how researchers must adapt their research protocols to the life style of the creatures they are studying
Program Description
This video allows you to introduce an additional Science Standard, #6, added to those cited for programs 3 and 4: "Knows the general structure and functions of cells in organisms," (Project 2061, Benchmarks for Science Literacy, page 110.)
• "Seal Survival Strategies" (03:54) Portraits of the four most common species of seal found in Antarctica, with key statistics relating to size and diet. Elephant seals are the largest, with more red blood cells than any other animal, and more hemoglobin per cell. Leopard seals are the fiercest, sometimes eating penguins and even young seals of other species. Fur seals have fine coats which, in the past, made them a favorite target of hunters. Weddell seals (the endearing stars of our program) stay farthest south year-round, emerging each spring to nurture their young on the thick sea ice.
• "The 'Sealheads' " (03:51) OK, maybe it's not quite as dramatic as MTV's "Real World" but this location sequence authentically documents the daily life of the enthusiastic young researchers who spend months out on thick sea ice atop 2,000 feet of ocean near Big Razorback Island. Their cheerfully undertaken duties range from washing up breakfast things to the microscopic analysis of seal blood samples. Team leader Mike Castellini reviews why they are here: to compare thriving Antarctic seals populations with mysteriously threatened Arctic species, in what he calls a "pole-to-pole" comparison. He reminds us how carefully all USAP researchers are when handling native species, and notes they have never seen any negative effects from their handling of the young pups.
• "Learning to be a Weddell" (05:10) One of the key phenomena being studied by Castellini and researchers like Jennifer Moss is how young Weddells learn to hold their breath for long periods while diving. Moss relates this successful adaptation (which allows the Weddells to dive deep to catch their prey) to the months the pups can spend on the solid ice "learning" from their mothers. Castellini suggests that discovering more about how pups learn to hold their breath for long periods and then resume breathing normally may provide important lessons for our understanding of SIDS, Sudden Infant Death Syndrome, in humans. Laurie Rea describes why the "Sealheads" need to analyze blood, in portable laboratories out on the sea ice: secrets about cell structure and hemoglobin-carrying capacity would be lost in the journey back to base camp. It's this which make Weddells able to carry enough oxygen for 90 minute dives, and fits them so well for survival in Antarctica.
The combination of intimate portraits of the seal mother and pups, and the researchers who study them, make this a fascinating and eminently watchable program through which to reinforce the principles of adaptation to extreme conditions through natural selection. The video also shows researchers thoroughly enjoying hard work (see online JOURNALS for still more details.) Castellini has the last word: "It's always been an adventure for me, I've been coming here for almost twenty years now. When you leave the Antarctic, it's as if it's a dream world. There's nothing back anywhere else that you can compare it too, and that's what really keeps us going. Basically it's the science, because that's our job, but it's tremendously fun."
