saltwater – Discover-Nature

Seaside

Shorelines of oceans, seas, and large bodies of water around the world are habitats for plants and animals that thrive in challenging conditions. Tides occur twice each day when water levels rise over a six hour period to cover large areas before receding to leave those same areas open to the air until the next tide starts to move inland again.

^{Nearshore habitat zones by King County, WA;} ^{Littoral Zones by US Government}

Shoreline habitat has been classified into zones often known by many different names. The intertidal zone is the area affected by changing temperature and salinity conditions as water moves in and out with each tide. The subtidal zone is the lowest and is exposed to air only during extreme spring tides or storms. The backshore zone is the highest and is exposed to water only during extreme spring tides or storms.

^{Starfish & anemone in tidal pool by Jonathan Levy}

^{Sea urchin in tidal pool, Bahia de Banderas by Jim Hoffman, Mar 2017}

Many species of animals live in each zone and are adapted to living completely submerged as well as completely uncovered by water for several hours each day. They handle the change in temperature and salinity with exposure to air or water. Tidal pools may keep some animals submerged for far longer periods. Temperature, dissolved oxygen, and salinity change far less for these organisms.

Bryozoans by John Turnbull, Sep 2021; Sea anemone by Barb Ignatius; Squat lobster, Glathea rostrata, by FWC Fish & Wildlife Research Institute, Aug 2013

Some species can be found in every zone in the ecosystem, but many are anchored to rocks or dug into the bottom. Species may prefer one zone, but get washed into another zone by wave action. Many organisms have tough outer surfaces to put up with battering waves and exposure to sun and wind. All of the occupants are subject to a wide range of predators from those that move on dry land to underwater hunters. Let’s take a look at a few of the creatures able to live in these ever-changing conditions.

The sea anemone clings to rocks and protects itself by drawing in its tentacles to become a jelly-like blob. The squat lobster can be found under stones along the shoreline. Its tail is fan-shaped and facilitates quick escapes when the animal is threatened by pulling the lobster through the water with powerful strokes. Bryozoans are small filter feeding organisms protected by a hard exoskeleton that the animal can withdraw into for protection.

^{Dog whelk, Nassarius livescens, by Budak, Dec 2016}

A mollusk called a dog whelk is a stealth predator often found on rocky surfaces. It uses its tongue to drill through the shells of other mollusks, where it squirts a digestive juice into the prey’s shell which kills and partially digests the prey. The dog whelk then uses its tongue to suck up the soupy meal. The starfish is another fierce predator. It wraps its arms around a shellfish and pulls it apart. Upon opening the shell, the starfish pushes its stomach out of itself and into the prey’s open shell where it empties its digestive juices inside, and similar to the dog whelk, creates a tasty, soupy, meal.

Sea urchins can be found clinging to hard surfaces where they feed on algae and other small, encrusted animals. Fan worms look like a leathery tube among underwater rocky crags. Several feathery tentacles fan out into the water to filter out microorganisms flowing by.

Shorelines create a habitat that is constantly changing with tides moving in and out, inconsistent weather conditions, and a large variety of flora and fauna coming and going. Learn more about this fascinating habitat at the Jurica-Suchy Nature Museum or a natural history museum near you.

^{Botanical beach at Port Renfrew by James Wheeler; Feather Boa kelp in the surf by Kqedquest, May 2007; Rocky intertidal zone in Oregon by Minustide, May 2015}

White, Yellow, Green?

Polar bears, Ursus maritimus, live in the Arctic and are heavily dependent on the ice floes where they hunt, breed, and spend a majority of their lives, making them the only bear to be classified as a marine mammal. They are strong swimmers and are able to maintain a steady 6 mph swim speed for several hours, crossing long distances between ice floes. Polar bears are a relatively new species, having branched off from the brown bear family about 150,000 years ago. Their close family relationship enables them to breed with brown bears, and grizzly / polar bear cubs have been observed, although not often.

^{Polar bear, Ursus maritimus, walking on}
^{sea ice by vladsilver, Getty Images Pro}

^{Polar bear, Ursus maritimus, swimming in}
^{Arctic Ocean by FrankHildebrand, Getty Images Signature}

Many other marine animals inhabit the world of ice including the polar bear’s favorite prey: seals coming out of the water over the edge of an ice floe. Bears often wait at these locations for a chance to grab a seal with heavy, sharp claws. But seals are wary and slippery, and bears do not often capture them, losing 9 out of every 10 they hunt. Their white fur should help to conceal them against a background of snow and ice. But as you look at the following pictures, are they really white or yellow or tan or even green?

^{Polar bear in white by}
^{dagsjo, Getty Images Signature}

^{Polar bear in yellow by}
^{ekvals, Getty Images Signature}

^{Polar bear in green by}
^{Asten, Sep 2006}

A polar bear’s fur has a top layer of guard hairs and a bottom layer called the undercoat. Guard hairs are much longer and completely cover the undercoat. Both hair types are transparent with no pigment of any color. The guard hairs are hollow tubes filled with air that scatter visible light into all the different wavelengths of the spectrum. When we see a structure scattering light, it appears to be white. However, polar bears rarely look completely white, except in the spring after their annual molt when they shed their old fur and grow a new coat.

Most of the time, polar bear coats are shades of yellow or tan, possibly with some darker colors. Oils rubbed off from their prey, including fat from seal and whale bodies, tinge the fur in shades of light yellow or tan. When they are on land, constant contact with dirt and other environmental elements may add darker colors to their fur. Polar bears work hard to keep their fur clean and in good condition. When combined with a thick layer of fat on the inside of their skin, it is the best insulation against the outside environment where they live. Clean fur also provides good camouflage when stalking prey. They may roll in snow or wash off in the ocean to clean their fur.

^{Rolling in the snow by webguzs, Getty Images}

Bears that live in captivity, outside the Arctic, may display shades of green in their fur. Algae growing in warmer waters of captive environments gets inside the guard hair tubes, which make an ideal environment for it to grow. Neither saltwater nor extremely cold water, both found in Arctic environments, support the growth of algae. A long soak in saltwater is a popular restorative cure for bears in zoos.

^{Polar bear bathing at the zoo by iSailorr, Getty Images}

Come to see our polar bear at the Jurica-Suchy Nature Museum to learn more fascinating facts about this iconic species. For information or to make a reservation, please click here: Visit JSNM

Snake Defense

Snakes, with over 3,000 species worldwide, are one of the largest groups of reptiles. They are found on every continent except Antarctica and live in every type of habitat including freshwater and saltwater. They have numerous enemies and have developed defensive strategies enabling them to survive and prosper.

^{Catching a snake on the wing by CuriousLog, Jun 2007}

^{Red-shouldered hawk with snake by Don Loarie, Mar 2018}

^{Great Blue Heron eating snake by C Watts, Jan 202}2

Snakes must deal with threats from a wide range of animals. Bird species that prey on snakes include raptors, ravens, egrets , and storks. Nocturnal hunters, including owls, have excellent sight in low-light conditions and often hunt by spotting movement among foliage. Likewise, during daytime hours, red-tailed hawks and eagles can spot movement on the ground while soaring. Snakes are normally line-of-sight hunters, and are often unaware of threats from above, giving avian predators a distinct advantage.

_{^{American crocodile, Crocodylus acutus by Florida Fish and Wildlife, Feb 2021; Wolverine by Maia C, Aug 2012; Skunk by D Fletcher, May 2016}}

Most mammal predators are larger, more agile, and faster. Badger, wolverine, and racoon are all excellent climbers and may hunt from an elevated perch. Wolverine and skunk are also burrowers that will dig out their prey from underground. Snakes living in saltwater and freshwater environments are eaten by predators such as crocodiles and snapping turtles. In addition, some larger snake species regularly hunt smaller snakes.

^{Copperhead on dead leaves by Abbott Handerson Thayer, Mar 2022}

Snakes use a number of non-aggressive strategies to avoid confrontation and escape. Their best defense is to remain hidden, using colors and patterns to break up the outline of their body, allowing the snake to blend with the background foliage and be overlooked by any predators. Another passive strategy is balling, involving compressing their body into a tight coil or ball, typically with the head tucked in to protect this most vulnerable area. Playing dead is often an effective means to escape predation, honed to perfection by the Western hognose snake. This snake convulses its body, rolls onto its back, and lets its tongue loll out of its mouth. It may vomit or spew blood, release fecal matter or musk, all in its attempt to convince a potential predator that it is already dead and no longer appetizing.

^{Timber rattlesnake balled and hidden by Peter Paplanus, Apr 2022}

Mimicry is a development that has taken place in some species over long periods of time. Batesian mimicry is when a harmless species has evolved the coloration of a more dangerous species to fool a predator into leaving it alone. Scarlet kingsnakes of the southeastern United States are quite harmless but look very much like Eastern coral snakes, a venomous species in that same area. Auditory mimicry involves creating sounds used by more dangerous snakes. Fox snakes, found in deciduous forests, often vibrate their tails in leaf litter, making a buzzing noise very similar to the sounds made by rattlesnakes living in the same area.

^{Scarlet kingsnake by FWC Fish & Wildlife Research Institute, May 2015}

^{Eastern coral snake by FWC Fish & Wildlife Research Institute, Sep 2014}

Snakes often use one or more methods of intimidation. Bright display colors are found among many venomous species and serve as a warning to potential predators that this snake is dangerous. Another form of intimidation involves a snake inflating its body or a body part to make it look bigger. The puff adder inflates its whole body by filling its lung with air. Cobras hold their heads high and flare out an extra fold of skin on either side of their heads, commonly called “hooding.” Intimidation may also involve auditory cues including the rattling of a snake’s tail and the hiss emitted by cobras as they bring up their heads.

When the above strategies do not allow the snake to escape, most species will not hesitate to strike. Several species do not bite, striking with the nose or an open mouth; however, all venomous snakes will bite in self-defense, although they may not inject venom. A few species are able to spit venom, used purely as an act of self-defense, although if the venom targets an eye or nasal passage, the results can be extremely painful.

Snakes are some of the most interesting species with a lifestyle very different from our own. They have many strategies for keeping themselves safe from wild predators, and will be around for us to observe, learn about, and be fascinated by.