Creature Feature: Beluga Whale

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Scientific Name: Delphinapterus leucas

Size – 13 to 20 feet, 2000 to 3000 pounds

Life span – 35 to 50 years

Diet – Fish, crustaceans, and worms

 

Beluga whales are born to stand out—with their unusual white color, they are easy to spot and recognize. They aren’t always this color though. Baby Belugas are born gray or brown, and then fade to white as they mature sexually.

Compared to most whales, Belugas are small, ranging from 13-20 feet in length. They are also unique because they lack a dorsal fin, something most fish and marine mammals have. There are several other things that make Belugas special. They have a more complex way of communicating with one another, utilizing clicks, whistles and clangs, along with other sounds that they sometimes mimic.

Beluga whales can be found in the coastal waters of the Arctic Ocean, and in subarctic waters as well. Belugas almost always live and travel in small groups call Pods. They migrate south when the ocean begins to freeze over and have to move quickly, otherwise they could be trapped under the ice and suffocate—or become an easy target for predators, like Polar Bears.

You might wonder why Beluga whales live in such a frigid environment. They have a thick layer of blubber (which can be as thick as 5 inches!) to help keep them insulated and warm. They also have a hard dorsal ridge along their back and a tough forehead, which helps them to swim through the icy sea water.

Beluga whales are truly amazing and beautiful creatures. Should you ever be near arctic waters, take some time and see if you can spot these fantastic white whales! They are worth the wait.

Sources: http://us.whales.org/species-guide/beluga-whale

http://www.defenders.org/beluga-whale/basic-facts

http://animals.nationalgeographic.com/animals/mammals/beluga-whale/

Written by: Kari Shirley, intern

Creature Feature: Spinner Dolphin

Common Facts:

Scientific name – Stenella longirostris

Diet – Small fish and squid

Size – 6-7 feet, 130-170 pounds

Lifespan – up to 20 years

Most of us are familiar with dolphins—the fun and playful porpoises that can often be seen leaping out of the water to socialize with each other and with humans. One type of dolphin that you may not be as familiar with is the Spinner Dolphin.

Spinner dolphins are named after their above the water theatrics—they love to leap out of the water and spin a few times on their body axis while doing so. Some can spin as many as four times around in one leap.

These dolphins love to stay together and are usually found in huge groups. They do their hunting at night, feeding mainly on mid-water fishes and deep-water squid, and then they rest during the day time.

Spinner dolphins can been found all over the world, mainly in tropical and subtropical oceans. For some reason, Spinners tend to follow groups of Yellowfin Tuna around. Because of this, fishermen seeking Tuna will often track the dolphins in order to get to them. Oftentimes, the dolphins are caught in the nets with the tuna, and because of this, their population is decreasing.

Thankfully, “Fishing methods for tuna imported into the U.S. under the Dophin-Safe program do not allow fishing practices, such as setting on dolphins.” The Spinner Dolphin population is at a stable number right now.

So if you are ever in a warm and tropical area, close to the ocean, stay alert to see if you can see any Spinner Dolphins. If you do, you are in for a show!

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Sources: http://acsonline.org/fact-sheets/spinner-dolphin/

http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/spinnerdolphin.htm

Written by: Kari Shirley, intern

Creature Feature: Megamouth

Megamouth-shark Bruce Rasner Rotman Arkive

This week’s shark is strange and mysterious. The Megamouth Shark (Megachasma pelagios), as you can guess, has a bulbous head and large mouth that contains many rows of small hooked teeth. Since the discovery of the Megamouth in 1976, there have been many hypotheses about its evolutionary background based on its feeding apparatuses and other physical features. Its unique features lead to the description of a new family, genus, and species was formed.

Some light has been shone on this little-studied shark. In 1990 a Megamouth Shark was tagged and tracked near Dana Point, California. The tracking data from this shark showed that it dove deep during the day and returned to the surface at night. This pattern of diving and surfacing is known as vertical migration. Many animals including squid, krill, and other zooplankton also exhibit vertical migration. Megamouths feed primarily on krill, so it is believed that they migrate to follow their prey.

Does such a large shark have any predators? While rarely seen, there is some evidence that they are preyed upon by sperm whales, which leave visible scars. Megamouths are also food for parasites including the Cookiecutter Shark (Isistius brasiliensis), which also leaves bite marks and scars. Click here to read more about Cookiecutter Sharks. Megamouths also host internal parasites including cestode and typanorhynch worms.

Join us nest week to read about the final shark of the year!

Edited by Felicia Van Stolk
Picture courtesy of ARKIVE : Bruce Rasner/Rotman/naturepl.com 

 

Creature Feature: Megalodon

Megalodon_scale1

MEGALODON! This ancient shark has captivated scientists and shark enthusiasts since the first fossilized tooth was discovered. Some people have even­­ speculated that it still roams the deep and unexplored areas of the ocean, though the scientific evidence is patchy. As an educator of marine science, I have taught about sharks for many years and the Megalodon is always an inevitable topic of discussion for curious students. In recent years (and in light of one particular 2 hour Discovery Channel mockumentary special that shall remain nameless) more students have approached me with questions, believing that this massive shark continues to exist today. In this post, I will highlight some facts and theories about this massive creature.

There is a great deal that researchers can hypothesize about ancient sharks by observing their present day cousins. Many of the theories on prehistoric shark behaviors are based on what we know of sharks we can see today like the Great White, or our own Leopard Shark. Like other sharks that swim in our ocean today, the Megalodon skeleton was made of cartilage. Unlike hard bone, cartilage cannot fossilize over millions of years; therefore much of what scientists have learned about this shark’s physiology is based on evidence left by fossilized teeth. From estimates of the ratio of tooth and jaw size to body length, paleoichthyologists (those are scientists who study ancient and fossilized fish) guess that the Megalodon could have been as large as 60 feet long. To get an idea of how big a Megalodon might look, imagine the length of an average school bus – that’s 45 feet long! The Megalodon was MEGAHUMONGOUS! Fossil records have also helped us to determine the time period during which of this shark ruled the ocean, which was around 16 million to 2 million years ago.

Megalodon tooth Cory DoctorowFossils can only tell us so much, but even though the reason for Megalodon extinction is not known, there are theories. One theory is that of the changing ocean properties. During the era in which we think Megalodons lived, the ocean was warmer than it has been in the last few ages. At a certain point in history, the earth began to change and the water temperature began to cool. Some scientists believed that the Megalodon was not able to evolve the ability to maintain an elevated body temperature, an adaptation known as endothermy.

There are many more theories surrounding the mysterious Megalodon, so dive into some research and take a look for yourself! Read some of the amazing scientific journals, books, and articles to learn even more about this fantastic, prehistoric, and most likely extinct (sorry Discovery Channel) shark.

Edited by KC O’Shea

Photography: https://commons.wikimedia.org/wiki/File:Megalodon_scale1.png and Cory Doctorow

Creature Feature: Whale Shark

Whale-shark-feeding Ron and Valerie Taylor Arkive

Do you know which is the largest fish in the world? Even though it is not a whale (whales, unlike fish are mammals you Whale-shark-teeth Jurgen Freund Arkiveknow) you could say that it is a whale of fish!

Give up? It’s the Whale Shark (Rhincodon typus) reaching up to 60 feet. Such a big animal might sound intimidating, butWhale-shark-gills Adam Broadbent Arkive
don’t be alarmed. This shark is extremely docile and doesn’t even like to eat organisms any larger than a small goldfish. Whale Sharks prefer plankton, which are mostly microscopic drifting organisms.
Whale sharks have very helpful adaptations which allow them to feed on tiny planktonic plants and animals. One of these adaptations is the large mouth located almost at the tip of the snout. They are able to open their mouth really wide and are able to filter plankton from the water through internal sieve-like screens and out through their gill slits.

In addition to being humongous, Whale Sharks have flattened heads and blunt snout, making them easy to distinguish from other sharks. The color pattern on this shark’s body is brownish gray with white spots and vertical stripes on the dorsal (top) side and white on the underside.

Whale Sharks like to live in tropical waters and are a popular animal for local tourism in Australia. Who wouldn’t want to swim alongside these gentle giants? Sadly, these massive beauties are still being hunted in parts of Asia and are considered a vulnerable species.

Join us next week as we begin to look at strange and unusual sharks found through history.

References:
Edited by KC O’Shea
Photography: Ron and Valerie Taylor, Adam Broadbent, and Jurgen Freund Courtesy of ARKIVE

Creature Feature: Bamboo Shark

Brownbanded-bamboo-shark-close-up D.R. Schrichte

Not all sharks spend their lives in the deep, open waters of the ocean. Some sharks prefer the shallows. You will find a small shark called Brown Banded Bamboo Shark (Chiloscyllium punctatum) in the tropical waters of the Indo-West Pacific. Only reaching about 3.5 feet in length, they can be spotted hiding out in crevices of coral reefs, along sandy and muddy substrates. There are even accounts of this shark residing in tidepools! What special adaptations do these sharks have that allow them to survive in these habitats?

Juvenile-brownbanded-bamboo-shark-bands-starting-to-fade Doug PerrineLike many creatures in inhabiting diverse ecosystems, one special attribute of this shark is its coloration and pattern. The young will have “bands” across its body while the adults are light brown. This allows the species to camouflage with the shadows cast by its surroundings. Their camouflage protects them from predators and masks their presence to unsuspecting prey. When the bamboo shark feeds, it creeps out of its hiding place at night and kicks up the sand, shocking and blinding its prey. They feed on bottom-dwelling (remember that word “benthic”?) organisms and small fish.

Another useful adaptation is the ability to survive in water with low oxygen levels. This phenomenon is known as environmental hypoxia. It is vital for creatures that live in an environment where the levels of dissolved oxygen can become so low that it cannot support aquatic life, as is often the case in tidepools. Tidepools are formed as the tide goes out and pools of water get trapped in crevices in and between rocks. This happens twice a day. The sun warms the pools causing evaporation and a decrease in oxygen. The organisms living in these pools use up the existing oxygen and those with various adaptations, like our bamboo shark are able to survive. Now that’s pretty amazing!

Join us next week as we look at a relative of the bamboo shark.

References:

Edited by KC O’Shea
Photography: Pictures from ARKIVE– D.R Schrichte  and Doug Perrine
http://www.flmnh.ufl.edu/fish/Gallery/Descript/bbambooshark/bbambooshark.html
Bennett, M.B. & Kyne, P.M. (SSG Australia & Oceania Regional Workshop, March 2003) 2003. Chiloscyllium punctatum. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 29 July 2015.

Creature Feature: Lemon Shark

Lemon Shark Tomas Kotoug Arkive

Lemon Shark (Negaprion brevirostris) is a blunt-nosed and powerful shark reaching up to 11 feet in length. While their color is yellowish to greyish and lacks any distinct markings, they do have two large, almost equal size, dorsal fins which distinguish them from other sharks. The coloring of this predator helps it live in coastal tropical habitats along the Western Atlantic from New Jersey, USA to southern Brazil as well as the west coast of Africa and eastern Pacific, from Baja California to the equator. They have a high tolerance for shallow areas with low oxygen levels, such as those with sea grass, mangroves, and bays.

Young Lemon Sharks have a tendency to stay close to their habitat but adults will often travel to deeper waters. It is thought that they have seasonal migration due to their feeding habits. Lemon sharks love to feed on a variety of osteichthyes (remember the science word for bony fish?), rays, guitar fish, crustaceans and mollusks.

Lemon-shark  Andy MurchThese are common sharks and are fished for both commercially and recreationally. Their meat is often dried, salted and smoked like jerky, while their fins are also a popular commodity. They are known to be a great “aquarium shark,” meaning they do well in aquarium habitats, and are often used in research.

For some reason, the population of lemon sharks in the Florida region has been depleting. Scientists have not isolated a specific cause and as of now there is no management plan. However, collecting knowledge about the species through research is always helpful, should the time ever come to create such a plan.

Check in next week to start our month on sharks that are found in the East Coast of South America.

References:
Edited by KC O’Shea
Photography: Andy Murch and Tomas Kotouc. Courtesy of ARKIVE
http://www.iucnredlist.org/details/39380/0
http://www.elasmo-research.org/education/ecology/estuaries-lemon.htm
Tricas, Timothy C., Kevin Deacon, Peter Last, John E. McCosker, Terence I. Walker, Leighton Taylr. A Guide to Sharks & Rays. San Francisco: Fog City Press, 2002. Print
http://video.nationalgeographic.com/video/shark_lemon

Stewardship Monday: Plankton Soup

“How fast can the fastest plankton move? How short-lived is the shortest-lived, and how long-lived is the longest-lived plankton?” Plankton has always captured the interest and imaginations of our students, and they are more popular than ever thanks to certain under-the-sea television characters. And well it should be, plankton is extremely important to life both in the ocean and on land. Though most plankton is microscopic, it is responsible for producing a majority of Earth’s oxygen, capturing CO2, and being the base of the oceanic food web.

The first question is, “What is plankton?” Plankton is a category of living things that live in any natural body of water and cannot move or swim against a prevailing current (although they can move). This group of drifters in incredibly diverse, including bacteria, single-celled plants, tiny animals, and even giant jellies! Because this group is so diverse, determining the life-span is difficult. Life-spans may range from a couple of days to several years, to possibly infinity (check out the “immortal jellyfish”)!

The “fastest” plankton, is actually the fastest animal on the planet! With consideration given to its size, the fastest animal is the copepod. “If it were the size of a cheetah, it would be able to run at 2,000 miles per hour” (http://www.classroomatsea.net/facts). The copepod is the model for the famous Plankton character, and our students are always excited to see it here in the San Francisco Bay. 

Plankton don’t have to be racers like the copepod to move quickly. Copepods move in small bursts of speed, but like all other plankton, they also drift with the currents. The fastest currents include the Florida Current flowing into the Gulf Stream from the Carribean to the North Atlantic, and the Agulhas Current from Mozambique down the south east coast of South Africa. Both of these currents have pak speeds of about 2m/s.

These currents carry plankton quickly around the ocean. They also carry other things in the water, dispersing them far and wide. Trash, especially plastic, can move in currents just like plankton.

Stewardship action: let the plankton ride the currents, not the plastic! Reduce your plastic use, and make sure plastic ends up in the recycling, not the trash or on the ground!

Creature Feature: Blobfish

This week’s creature flopped on to the blog just in time for Halloween. It is creepy, weird, and funny looking and that’s why our super rad MSI Instructor Naomi likes the Blobfish, Psychrolutes marcidus. EEK!!

 Blobfish smithsonean

You might be thinking, That is not a fish.  That is a pile of goo that someone molded in something vaguely fishy and cartoony.  However, the aptly named blobfish has a good reason for looking so goofy.  Blobfish do not live by the surface of the water. They live thousands of feet under the ocean in Australia!

Fish that live higher up in the water have a swim bladder. This bladder is filled with gas so that the fish can maintain buoyancy when it moves around. If you are a blobfish though, having a swim bladder is a bad idea.  If the blobfish had a swim bladder, the depth pressure would compress so much that the fish would die. There is about 120 times more pressure deep in the water compared to the surface! So instead the blob fish has more of a gelatinous body with minimal bones so that the pressure would not squish them.  In short, the blobfish looks like goo so that it doesn’t explode!

So remember: things in nature are often ugly for a very good reason.  Next time you call the blobfish ugly, know that you would look weird too if you lived down in the deep.

Reference:

Edited by KC O’Shea

Photography: http://public.media.smithsonianmag.com/legacy_blog/09_13_2013_blobfish.jpg

http://www.mnn.com/earth-matters/animals/photos/13-of-the-ugliest-animals-on-the-planet/blobfish

http://www.smithsonianmag.com/smart-news/in-defense-of-the-blobfish-why-the-worlds-ugliest-animal-isnt-as-ugly-as-you-think-it-is-6676336/?no-ist

http://www.fishbase.org/summary/Psychrolutes-marcidus.html

Creature Feature: Jeweled Anemone Hermit Crab (Dardanus gemmatus)

Photography by John Cooney

Photography by John Cooney

Today we are going to talk about a marine creature that is seriously resourceful when it comes to real estate:  the hermit crab!  You may already know that hermit crabs are well known swapping their shell homes for newer, bigger ones.  Like all crabs, the hermit crab possesses an exoskeleton that protects their body and maintains their form. However, hermit crabs take self-protection one step further by finding snail shells and coil their body inside, protecting their softer body parts from predators and environmental elements. When they grow too large for their shell home they will crawl out and find a new snail shell that fits perfectly. Anemone hermit crabs go one step further to make their home safe.

In past posts we have talked a lot about symbiosis. Anemone hermit crabs have a mutualistic relationship, which you will remember is where both organisms benefit. Carlie Cooney, MSI’s Land Program Manger recently was able to view a jeweled anemone hermit (also known as Dardanus gemmatus) while on a dive trip at Garden Eel Cove outside the Kona airport. Carlie’s cool fact about these accessorizing little crabs is that they will grab small anemones and attach them to their shell. Not just any old anemone will do – even when moving to a new shell, the crab makes sure to transfer the same anemone to the new location. There are typically two species of anemones associated with the jeweled hermit crab, Calliactis polypus and Anthothoe sp.

Jeweled anemone hermit crabs benefit by having extra protection due to the stinging anemone tentacles.  The anemones also can be placed on top of cracks or weak spots in the hermit crab’s shell.  Plus, anemones make for amazing camouflage among the rocks and corals. In return the sea anemone gets scraps from the food that the hermit eats and gets to piggyback to areas that are productive in nutrients. Anemones aren’t the only ones hitching a ride.  The jeweled hermit crab will also carry flatworms and amphipods, unwittingly housing an entire traveling community on its back!

References:

Edited by KC O’Shea

Photography by John Cooney https://www.flickr.com/photos/jmtb02/sets/72157647477618880/

http://www.hawaiianatolls.org/research/CoML/features/anemonecrabs.php

http://www.nrcresearchpress.com/doi/abs/10.1139/z70-056#.VC6rgfldUsc

 

 

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