Fossil records indicate that the ancestors of modern seals first entered the ocean on the west coast, about 28–30 million years ago.

Like all marine mammals, seals get all the water they need from their food. Their bodies are very efficient at removing and recycling water from their food. They avoid drinking sea water; if a seal drinks too much sea water it can become seriously sick. Arctic seals, which spend time on ice, may sometimes eat fresh water ice and snow.

Seals do not need to be wet constantly. They come out of the water to get dry; wetting them is actually a form of harassment.

Males’ coloration is typically darker than females’. Males are dark brown, gray, or black with smaller, lighter spots. Females have a tan or light gray background with darker spots.

Their most distinctive feature is the shape of their head. They have been nicknamed “horse-heads” because of the long, straight, slope of their profile.

Harp seal

A seal’s body stores enough fat in the blubber layer to allow the animal to go for extended periods of time without eating. In addition, most seals are opportunistic feeders and will consume a variety of fish, shellfish, and crustaceans. Seals do not eat on land.

With some exceptions, greases with different types of thickeners should be considered incompatible with each other. We recommend running grease compatibility tests if mixing different greases is unavoidable. Generally, incompatible greases will soften or become fluid. This can result in lack of lubrication and can lead to premature bearing failure. However, stiffening may occur and can also lead to a lack of lubrication. Always purge as much of the old grease as possible, and then regrease more frequently to purge all the old grease out of the bearing.

Seals make many sounds both out of the water—like elephant seals, and under water—like harbor seals. Scientists have recently started to use the sounds harbor seals make during mating season to identify and track them.

Seals, sea lions and walruses are currently placed in a sub-order, the Pinnipedia, of the Order Carnivora (which includes bears, dogs, racoons, weasels, hyenas cats, and mongooses). There are many recent studies on the genetic and fossil history of these groups and their place in the scheme of mammalian classification may well change in the near future.

Monk seal

In New England, harbor seal pupping occurs between mid-May to mid-June. Mothers nurse their pups for 4-6 weeks and will temporarily leave them during foraging trips.

Adult harbor seals will usually retreat to the water when approached, but juveniles will often remain on the beach. They are commonly seen resting on their side in a “banana” shape, on rocks along the coast.

Seal mothers and pups (as opposed to other pinnipeds) generally stay close together on shore and are not separated while nursing. Harbor seals are an exception, and mothers will leave pups on shore to feed offshore. Seal mothers and pups can stay in contact by sound. Harbor seal pups make distinctive calls that can be heard for up to a kilometer. When in close contact mothers and pups can identify each other by scent, recognizing scent from glands in the skin of their flippers and around their muzzles. If you see a harbor seal pup on shore, observe it from a distance and do not approach—its mother may be offshore. Seal pups are naturally attracted to moving objects that are bigger than they are. This can help a pup stay near its mother, but can also make a pup follow things that it shouldn’t (like you).

• Viscosity: Oil viscosity should be appropriate for the load and speed of the application at operating temperature. Technical Topic Guide to Electric Motor Bearing Lubrication This will help to insure maximum protection and component life. The typical mineral oil viscosity in an electric motor grease is in the range of 500 to 600 SUS at 100°F. Your electric motor builder may provide a specific recommendation.

The latest harbor seal stock assessment reports indicate that the minimum population estimate is around 66,884 animals. This includes animals distributed from the eastern Canadian Arctic and Greenland south to southern New England and New York (occasionally down to the Carolinas). Trends in the harbor seal population are uncertain. There is evidence to suggest that the population may be declining, or perhaps shifting its distribution.

We don’t really know how seals navigate, but we do know that they are very good at finding their way while traveling at sea, in all types of weather conditions, day and night, while spending much of their time underwater. Recent improvements in tracking technology (satellite tracking, GPS tracking) has shown that seals can travel great distances and return to the same spots on shore with great precision. Grey seals can swim from Cape Cod to Nova Scotia in a matter of days.

Seals can hear very well both above and below water. They can hear high pitched sounds well above the range of human hearing.

There are two species of seals that breed in New England: harbor seals and gray seals. There are three other species that breed in the Arctic and occasionally can be found in the area: the harp seals (the most numerous seal in the Northwest Atlantic), the hooded seal (the largest seal in the Northwest Atlantic), and rarely, the ring seal (the smallest seal in the Northwest Atlantic).

seals中文

It is against the law to touch, feed, or otherwise harass seals. Harassment occurs when your behavior changes their behavior. If your presence causes any of the following reactions on land or in the water, then you are too close:

The proper lubrication of electric motor bearings is essential to maintaining them in peak operating condition and, ultimately, in reducing unnecessary downtime. This bulletin, for Thermal fluids Hub customers, is intended to serve as a practical guide to the proper lubrication of electric motor bearings utilizing grease as a lubricant. It can help you to apply Thermal fluids’s years of lubrication experience with that of bearing and motor manufacturers from around the world to provide you with a guide to the proper lubrication of electric motor bearings.

Weddell seal

Grease is frequently used as an electric motor bearing lubricant because of its simplicity of application and unique characteristics. The primary functions of an electric motor bearing grease are to:

Male gray seals are characteristically larger than females. The average size of a male gray seal is approximately 7-8 feet in length and between 660-770 pounds in weight. Females will average approximately 6.5 feet and between 330-450 pounds in weight.

Northern fur seal

Three families of living pinnipeds are recognized, the Phocidae (hair seals or true seals), the Otaridae (fur seals and sea lions) and the Odobenidae (walrus). The term pinnipedia translates from Latin as "fin foot". All of these animals must come ashore to breed, give birth and nurse their young. Some species are at sea for several months at a time while others return to the shore every day.

Gray seals are born from mid-December to early February. In the United States, pupping takes place on islands in Penobscot Bay and Frenchman Bay, Maine, and on Muskeget, Tuckernuck, and Monomoy Islands in Nantucket Sound, Massachusetts. Mothers nurse their pups for approximately 16 days. After pups are weaned, mothers may leave the colony but pups remain for several more days or weeks living off blubber reserves.

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Sea lion

• Consistency: A grease’s consistency is one of its most visible characteristics. A grease’s consistency or firmness is stated in terms of its NLGI (National Lubricating Grease Institute) grade, which ranges from 000 to 6. The consistency of a grease should be appropriate to the application, as it affects pumpability and ability to reach the areas to be lubricated. A NLGI 2 grade grease is the most commonly used in electric motor applications.

It is absolutely normal for seals to be on land. Seals are semi-aquatic, which means they often spend a portion of each day on land. Seals need to haul out for a variety of reasons: to rest, give birth, and molt (annual shedding of old hair). Young seals may haul out on land for up to a week.

Harbor seal

• Shear Stability: ASTM D 217 Cone Penetration of Lubricating Grease test measures the consistency of the grease after it has been worked 100,000 strokes. An electric motor bearing grease should soften no more than 1 to 1.5 NLGI grades in this test. An electric motor bearing grease that softens more than that may leak out of the bearing with age.

• Dropping Point: The dropping point gives an indication of the temperature at which the grease will melt or the oil will separate from the thickener. Due to the high temperatures that can be reached in an electric motor bearing, a grease with a high dropping point is frequently desirable. Lithium complex greases and polyurea-thickened greases both have dropping points of approximately 500°F or higher.

• Oxidation Resistance: Electric motor greases should have outstanding resistance to oxidation. This extends the life of bearings running at high speeds and high temperatures. ASTM D 3336 High Temperature Grease Life test results give a good indication when operating under extreme conditions. Choose a grease with a high ASTM D 3336 oxidation life.

We do not have a good estimate of how many gray seals are currently in U.S. waters. Canadian population models estimate that there are likely around 505,000 in Canadian waters. Gray seal abundance appears to be increasing.

Grease is a semi-solid lubricant composed of a base oil, a thickener and additives. These components are combined in complex chemical reactions under controlled temperatures and pressures. The base oil used in greases may be mineral or synthetic. Mineral oils are adequate for most electric motor bearing applications. However, synthetic base oils may be required for extreme temperature applications or where longer re-greasing intervals are desired. The thickener primarily serves as a carrier for the oil and prevents it from leaking out of the application. Some common thickeners include metallic soaps that can be composed of calcium, lithium, sodium, aluminum or barium and complex metallic soaps such as lithium-complex. A thickener increasingly employed in electric motor bearing lubrication is polyurea. Polyrex EM utilizes a polyurea thickener. As with many lubricating oils, additives are frequently used to impart special properties to the grease. Commonly used additives include, corrosion inhibitors, antiwear or extreme pressure agents, oxidation and corrosion inhibitors, pour point depressants, lubricity agents, and dyes or pigments.

• Anti-Wear: Unless a motor is mounted so there is a thrust load on the bearings, it is generally advisable to use a grease without extreme pressure (EP) additives. EP additives can shorten the life of the grease and should not be recommended where they are not needed. On the other hand, bearings designed to handle heavy thrust loads may require a grease with an EP additive.

Seal

Seals see very well under water—better than they do in bright light above water. Their eyes are adapted with round lenses (like fish) and a large iris that fully opens underwater. On land the iris closes the pupil to a small pin point that lets the seal see clearly through the round lens. A seal’s eye is also adapted for low-light vision with a lining (similar to a cat’s eye) that reflects and amplifies the weak light at depth in the ocean.

The average size for a male or female adult harbor seal is approximately 4-5 feet in length and 220-250 pounds. Their coloration ranges from dark gray to tan and is overlaid with many leopard-like spots. They have small heads, very large eyes, and a face that resembles a cocker spaniel.

Single animals will usually stand their ground when approached, while herds/groups of gray seals will generally retreat to the water. They can be very vocal and aggressive.

Last updated by Northeast Fisheries Science Center on 05/03/2022

Scientists think seals can use their whiskers to feel vibrations from swimming prey. Blind seals in the wild seem to be able to hunt and feed without sight.

Warming ocean waters are bringing the sharks further north for longer periods of time. Seals are a prey source of marine mammal eating sharks, so this and the growing gray seal population may be the reasons we are seeing more great whites closer to shore in Massachusetts when seals are present during the summer. For safety, never swim near seals or haul out sites.

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