More Marine Animals
Marine Animals: Dall's Porpoise
The Dall’s Porpoise Phocoenoides dalli, is one of the fastest animals in the ocean, and the fastest cetacean. These porpoises can swim as fast as 35 miles per hour. The great speed of the Dall’s porpoise allows it to effectively elude predators and hunt prey. The diet of the Dall’s porpoises consists primarily of small fish and cephalopods. They are known to dive to depths of over 300 feet. Dall’s porpoises are commonly hunted by killer whales and great white sharks.
Porpoises are closely related to dolphins, differentiated from dolphins by their spade-shaped teeth, triangular dorsal fins, and the shape of their heads, which are compared in contrast to a dolphin’s elongated jaws. The Dall’s porpoise is identified by its thick body, small head, and coloration similar to that of killer whales. Their dorsal side and most of their body are dark grey or black, with white patches on their sides and belly. The tip of their dorsal fins and flukes may also be white or grey. Dall’s porpoises, and porpoises in general, are smaller than dolphins and whales. They grow to lengths of 7.5 feet and weigh between 290 and 490 pounds. Males are general larger than females.
Unfortunately, the Dall’s porpoise’s great speed cannot help it outrun other threats. These cetaceans are commonly caught in fishing nets, becoming completely stuck or dragging the net along with them, hindering their swimming speed and making them unable to hunt or avoid predators. Dall’s porpoises are also hunted for food by Japan, the only country to still do so. Japan harvests 18,000 porpoises annually. Pollution and noise from human activities also have a negative impact on Dall’s porpoises.
Marine Animals: Sperm Whale
The famous novel Moby Dick by Herman Melville recounts the tale of Captain Ahab and his quest for revenge against the great whale that bit off his leg on a previous voyage. The whale in this story is likely based on sightings by whalers of the star of today’s show, the sperm whale.
The sperm whale, Physeter macrocephalus, are the largest toothed whales. Their most distinguishing trait is their enormous, squarish heads that account for around one third of their body length. Their dorsal and pectoral fins are quite small when compared to the size of their bodies, with the dorsal fins often rounded. These whales are dark grey in color, with white patches on their underside. They have between 20 and 26 teeth set in a narrow jaw. Sperm whales can be found globally in deep water, from the equator to high latitude regions.
Sperm whales dive to catch their food, commonly achieving depths of 2000 feet where they remain for around 45 minutes. While diving, sperm whales hunt for large animals like squid, sharks, and fish. They return to the surface to breath and rest in between dives, usually for around nine minutes.
Sperm whales were once heavily targeted by whaling ships for ambergris and spermaceti. Ambergris is a waxy grey substance produced in the digestive system of whales to coat hard sharp objects eaten by the whale, such as squid beaks. It was highly valued as a component of perfumes in the past. Spermaceti is produced by the spermaceti organ in the heads of sperm whales, which may contain as much as 1900 liters of spermaceti. This substance was sought for use as a lubricant and in cosmetics. For sperm whales, spermaceti may alter the whale’s buoyancy as it dives, help to focus echoes and clicks in the whale’s echolocation, or cushion the head in some way.
Marine Animals: False Killer Whale
The false killer Pseudorca crassidens, is neither a killer whale nor a whale at all, but a large species of dolphin! When it was discovered, the skull of this cetacean was determined to be very similar to that of the killer whale, Orcinus orca, which lead to its description as “false killer whale”.
False Killer Whales grow to between 15 and 17 feet long, with females growing on average 1 to 3 feet shorter than males. Their characteristic features include dark grey or black skin, with a light patch of skin on the underside of the neck below the eye. With streamlined bodies, these dolphins are powerful swimmers.
False killer whales inhabit tropical and semitropical regions around the world, usually in open ocean waters but venturing into coastal waters occasionally. Populations have been found in Hawaiian waters and the Gulf of Mexico. The Hawaiian population of False Killer Whales is classified as endangered; numbers of Hawaiian False Killer Whales have declined at a rate of 9% per year since the early 2000s. A survey conducted in 2010 estimated the size of this population of False Killer Whales to be around 1550 individuals. Unfortunately, the Hawaiian False Killer Whales are the only well studied population in United States waters.
Fisheries are the primary threat to False Killer Whales. False Killer Whales try to eat bait or fish caught on commercial fishing lines, becoming hooked or entangled leading to serious injury or death. Commercial fisheries target many of the same species False Killer Whales feed on, including tuna, billfish, wahoo, and mahi mahi. Other threats include exposure to toxic chemicals from pollution, resulting in disease or damage to the reproductive systems of False Killer Whales.
Marine Animals: Stellar Sea Lion
Have you heard? The Stellar Sea Lion, Eumetopias jubatus, is the largest eared seal. Eared seals, which include sea lions and fur seals, belong to the family Otariidae. As their name suggests, eared seals have a visible ear flap, unlike true seals which have no visible ears. They were named after Georg Wilhelm Steller, a German naturalist who wrote about them while on an expedition in 1742.
The Steller Sea Lion can be found in coastal North Pacific waters. They are similar in appearance to California sea lions, but are much larger and lighter in color, with light tan or reddish-brown fur. Steller Sea Lions are sexually dimorphic; males are larger than females, up to 11 feet long and weighing 2,500 pounds. Females can grow to 9.5 feet long and weigh up to 800 pounds.
Steller Sea Lions depend on both land and sea to survive. They forage in coastal and open ocean waters for food. They feed on a wide variety of fish, including salmon, cod, sand lance, and are known to eat cephalopods, as well. On land, Steller sea lions rest, molt, and breed and nurse their young.
In the past, Steller sea lions have been hunted for meat, fur and oil, as well as being killed to prevent predation on farmed fish. In 1990, they were listed as threated under the Endangered Species Act. Currently, the National Oceanic and Atmospheric Association recognizes two different populations of Steller Sea Lions. The eastern population is considered threatened, while the western is endangered. The greatest threats to Steller sea lions today includes collisions with ships, pollution, and destruction of habitat.
Marine Animals: Stripped Dolphin
Did you know dolphins have names? Scientists believe that dolphins develop special whistles for other dolphins, which allows them to recognize and communicate with each other in the ocean, the same way humans identify each other.
The Striped dolphin prefers deep tropical or warm temperate waters, between 52- and 84-degrees Fahrenheit. These dolphins live in social groups called pods, consisting of between 20 and 100 individuals. They are dark blue or dark grey, with two distinctive stripes along the sides of their bodies extending from the eye to the pectoral flipper, and from the eye to the midpoint between their dorsal fin and tail fin. Males of this species of dolphin may grow up to 9 feet long and weigh 350 pounds, while females can grow to be 8 feet and 330 pounds. They may live to be nearly 60 years old. Striped dolphins hunt fish and cephalopods and are capable of diving to 2,300 feet.
Striped dolphins exhibit remarkable social behavior within their pods. Within a pod, striped dolphins are often organized into smaller groups based on age, sex or breeding status. They do not interact with other dolphins or whales. Many scientists and fishermen have observed stunning displays of acrobatics by these dolphins, spinning at the surface of the ocean or leaping high into the air.
Striped dolphins are not considered endangered or threated at this time, but they do face several considerable threats to their survival. The main threat to striped dolphins is entanglement in commercial fishing gear. Additionally, dolphins may face challenges from pollution and disease. 1,000 striped dolphins were killed in the Mediterranean Sea due to a disease outbreak related to pollution in the 1990s.
Marine Animals: Manatee
If mermaids existed, could they cope with climate change? Christopher Columbus once mistakenly reported a sighting of these mythical creatures when he sailed to the Americas. What he actual saw were manatees, describing them as “not half as beautiful as they are painted.” The legends of mermaids are apparent in the scientific name of the order to which manatees belong: the order Sirenia.
Manatees are large, migratory species of fully aquatic, herbivorous mammals commonly found in shallow, slow-moving coastal waters where seagrass beds or other vegetation grow. Manatees are gray-brown in color, with thick, wrinkled skin. There are three species of manatee: The west-Indian manatee Trichechus manatus, the Amazonian manatee Trichechus inunguis, and the West African manatee Trichechus senegalensis.
The West Indian Manatee is native to Florida. In 1997, population viability studies indicated Florida manatees would face extinction without protective efforts. Over the last few decades, populations of the West Indian Manatee have rebounded, with a recent population estimate of 6,100 individuals, up from an estimate of as low as 1,706 individuals in February of 1997. Despite their increased population, manatees are still considered threatened and face several threats, in particular collisions with boats. Manatees are slow-moving, and often struck by watercraft. Additionally, climate change poses a threat to manatees. Algae blooms, which may worsen due to climate change, were linked to the death of 166 manatees by killing seagrass on which manatees feed in July of 2012.
Marine Animals: Gray Whale
Gray whales are some of the greatest travelers in the oceans. Each year, gray whales migrate from North Pacific waters to equatorial waters off the coast of Mexico, a journey of over 10,000 miles that begins in the fall. The whales spend the winter months in warm waters where they breed before returning north in May. The gestation period of gray whales is around 12 months; mothers give birth every two to three years to a single calf, usually between fourteen and sixteen feet long and weighing as much as 2000 pounds. Gray whales can grow to lengths of 50 feet, weighting up to 90,000 pounds. They have a hump on their back, followed by a series of small bumps or knuckles along a ridge on their dorsal side. Their tail fins can be 10 feet wide, with a deep notch in the middle.
Gray Whales were called “friendly whales” in the seventies because of their curiosity and willingness to approach small boats. Their congeniality and curiosity may have put them at risk, as they were nearly hunted to extinction by commercial whaling in the 20th century. The Endangered Species Act of 1973 offered protections to the Gray Whale, and by 1994 the eastern North Pacific population of Gray Whales was determined to have successfully recovered. The western population of Gray Whales remains below 200 individuals today. Today, the greatest threats to Gray Whales include entanglement in fishing gear, collisions with ships, and noise pollution. Noise from ships and other activities confuses Gray Whales and can alter their migration patterns, or even cause strandings on beaches. Additionally, shifts in temperature due to climate change and overfishing are forcing whales to travel farther to find food.
Marine Animals: Right Whale
Old sailors can be blunt, but honest. If you were to ask a whaler in the 1800s which species of whale they were after, their answer would likely be the “right” one.
The common name of Eubalaena glacialis, the North Atlantic Right Whale, can be traced back to its high value as a target of whaling ships. Right whales were considered to be the ideal species to hunt because of their high blubber content, which makes them float after being killed, and because Right Whales commonly swim close to shore at slow speed. Oil and baleen were the primary reasons Right Whales were hunted. Whale oil was used as fuel for lamps or for producing soap. Baleen are bristle-like projections found in the mouth of some whales. The bristles are made of keratin, like your fingernails, and allow the whale to filter tiny organisms out of seawater. Baleen was used in a number of ways as a rigid but pliable frame for umbrellas, folding fans, or women’s corsets. Whaling massively depleted populations of Right Whale in the North Atlantic, and this species has been considered endangered since 1970.
Right whales can grow to be 52 feet long and weigh 70 tons. Their bodies are stout and black, lacking a dorsal fin. Their most striking features are patterns of rough skin on their heads called callosites. Callosite patterns on Right Whales are unique, like a fingerprint, and often appear white because they are covered in small crustaceans that feed on the whale’s skin. The diet of Right Whales consists primarily of zooplankton and copepods, which they filter out of the water with baleen. Right whales are acrobatic; they are known to breach, launching themselves into the air and returning to the water with a tremendous splash.