Lobsters are odd creatures. Despite their strange, even grotesque appearance and their nickname as the "cockroaches of the sea," lobsters are a tasty delicacy enjoyed by humans around the world. But lobsters are also quite sophisticated critters. A lobster's two claws can come in several different forms (crusher and cutter, two crushers or two cutters). It has four spindly antennae and sensing hairs that allow it to smell amino acid in its prey. And that prey could be a lot of things: lobsters eat up to 100 types of animals and, occasionally, plants. They're even known to munch on one of their vulnerable lobster brethren, though that's more common in captivity (it's also why captive lobsters have rubber bands on their claws). Lobsters sometimes bury their food and eat it over several days. They use teeth located in their stomachs, eat their molted shells (full of calcium) and can shed appendages if attacked, wounded or surprised, only to regenerate them later. Finally, lobsters live in a hierarchy and it's the females who do the courting.
But there's one lobster fact that trumps them all: lobsters show no apparent signs of aging. They don't slow down or become weaker or more susceptible to disease. They don't get infertile -- older lobsters are actually more fertile than younger ones. Most lobsters seem to die because of something inflicted upon them and not because a body part failed or broke down. They're such hardy creatures that scientists aren't even sure how old lobsters can get. Add in that lobsters grow throughout their lives, and one has to ask: Is it possible that a lobster born before Napoleon and as heavy as an NFL lineman is chowing down on the sea floor?
Since lobsters never stop growing, lobster age is generally determined by size, though they can grow at different rates depending on the environment. A one-pound lobster (the minimum size that can be eaten legally) is usually 5 to 7 years old, but lobsters raised in 70-degree water have reached two pounds in less than two years. The largest lobster on record weighed about 44 pounds. Presumably, the larger lobsters get, the more competition they face for food resources and the more attention they'll attract from predators. That could make life difficult for a mega-lobster.
Professor Jelle Atema of Boston University, who has studied lobsters for decades, wants to test the animal's limits. Right now, he has a 15-pound lobster living in a cage, free from predators and pathogens. Even in these idyllic conditions, it will be years before Professor Atema's lobster approaches any records.
We may have to check in with Professor Atema, or his successor, in a few decades to see how the monster lobster measures up, but in the meantime, let's consider why lobsters live so long and get so big, and what this means for other animals, including humans.
Big Lobsters and Eternal Life
Decline is an accepted part of old age for most people, even for those still searching for the fountain of youth. We expect the same in our pets and in the flies that buzz around us, albeit at a different rate. So why are lobsters different? A study conducted in 1998 showed that lobsters maintain telomerase activation late in life. But before we explain that, let's talk briefly about cell division.
Telomeres are like caps or sheathes that encase the ends of chromosomes. When cells divide, telomeres get shorter. When telomeres get to a certain length, they can no longer protect chromosomes and the chromosomes start to suffer damage. The number of cell divisions before damage sets in is called the Hayflick limit.
Telomerase is an enzyme that adds length to telomeres, extending their life span. In humans, telomerase is abundant in embryonic stem cells and then declines later in life. This is actually a good thing because when cells re-activate telomerase after reaching the Hayflick limit, they become cancerous (in other words, they don't die when they're supposed to). The downside is that cells with short telomeres weaken and die, so we eventually die, too.
In humans, telomerase levels decline later in life and are only found in some types of tissue, but in lobsters, telomerase is found in all types of tissue. That likely accounts for lobsters' ability to grow throughout their lives. And because lobsters' skeletons are on the outside and the molting process allows them to periodically shed their exoskeletons in favor of a new, larger one, their constant growth isn't a problem. With a steady, evenly distributed supply of telomerase, lobsters don't approach the Hayflick limit, which means that their cells stay pristine, young and dividing.
The dual role of telomerase in keeping cells healthy and in cancer growth means that it's an important area of research for both anti-aging and cancer treatments. Further study of lobsters may teach us more about their longevity, how long they can actually live and what that knowledge may mean for human health.
Scientists are also studying a variety of other animals that are long-lived. Like lobsters, many types of turtles don't show compromised immunity or physical breakdown because of age. They also become more fertile with age and usually die because of a predator or malady unrelated to age.
A bird known as Leach's storm petrel fits into a human hand yet lives more than 30 years. They're also the only known animal in which telomeres grow longer with age. Related animal species with vastly different life spans are also a point of interest. Conventional mice live only three years, but naked mole rats can live for 28.
Other animals being studied include whales, bats, rockfish, zebrafish and clams, the oldest of which, a quahog clam, lived to be 220 years old. In many of these animals, the rate of telomere deterioration corresponds with their lifespan. The longer the telomeres last, the longer the animals live. Studying these creatures may tell us much about human aging and lead to treatments for aging-related diseases. Exciting research is being conducted on many fronts -- on the molecular and genetic levels and regarding lifestyle, diet and habitat. If one day humans discover an important new treatment for cancer, it may be due to one of these creatures -- or to a 200-pound lobster living peacefully in a tank at Boston University.
For more information about lobsters and aging, and to hear a song about Leroy, the Uninterrupted Lobster, please check out the links on the next page.
Related HowStuffWorks Articles
More Great Links
- "Ageless Animals, the Lobster Edition." Methuselah Foundation. June 27, 2007. http://www.mprize.org/index.php?ctype=news&pagename= blogdetaildisplay&BID=2007062-27094442&detaildisplay=Y
- "Definition, Open Comments." Telomerase.org. March 26, 2007. http://www.telomerase.org/serendipity/index.php?/archives/14- Definition,-Open-Comments.html
- "Facts about lobsters." New England Aquarium. http://www.neaq.org/scilearn/research/subpage.php?id=25
- "Lobster Society: Behavior and Ecology." Gulf of Maine Aquarium. Feb. 11, 1998. http://octopus.gma.org/lobsters/society.html
- "Longevity of lobsters is linked to ubiquitous telomerase expression." Institute for Hematopathology, Center for Pathology and Applied Cancer Research. Christian-Albrechts-Universitat Kiel. Nov. 13, 1998. http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=retrieve&db=pubmed&dopt= AbstractPlus&list_uids=9849895
- Klapper, Wolframe, Kuhn, Karen, Singh, Kumud K., Heidorn, Klaus, Parwaresch, Reza and Krupp, Guido. "Longevity of lobsters is linked to ubiquitous telomerase expression." Institute for Hematopathology, Center for Pathology and Applied Cancer Research. Christian-Albrechts-Universitat Kiel. Dec. 3, 1998. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T36-3V7 JH3Y-12&_user=10&_coverDate=11%2F13%2F1998&_rdoc=1&_fmt= &_orig=search&_sort=d&view=c&_acct=C000050221&_version=1 &_urlVersion=0&_userid=10&md5=9278c04099d6ac1eb55fc4078e 754fb4#toc5
- Krulwich, Robert. "Long Live the Lobster: Forever Young?" NPR. June 26, 2007. http://www.npr.org/templates/story/story.php?storyId=11382976
- Yeoman, Barry. "Why Do Animals Age?" National Wildlife. March 2007. http://www.nwf.org/nationalwildlife/article.cfm?issueID=113&articleId=1440