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Humpback whales (Megaptera novaeangliae) are master migrators. Some populations of this baleen whale species travel upwards of 5,000 miles per year from colder waters to feed, towards warmer tropical waters where they give birth and care for their calves. However, new research on a population off Australia’s eastern coast indicates that their trips to more balmy waters are not as essential to calving as biologists thought……..Continue reading….

By: Laura Baisas

Source: Popular Science

Critics:

Humpback whale groups, aside from mothers and calves, typically stay together for days or weeks at the most.They are normally sighted in small groups, though large aggregations form during feeding and among males competing for females. Humpbacks may interact with other cetacean species, such as right whales, fin whales, and bottlenose dolphins. Humpbacks are highly active at the surface, performing aerial behaviors such as

breaching, surface slapping with the tail fluke (lobtailing) and flippers, and peduncle throws, which involve the tail crashing sideways on the surface. These may be forms of play and communication, and may help to remove parasites. The species is a slower swimmer than other rorquals, cruising at 7.9–15.1 km/h (4.9–9.4 mph). When threatened, a humpback may speed up to 27 km/h (17 mph).

Their proportionally long pectoral fins give them great propulsion and allow them to swim in any direction, independently of the movements of the tail. Humpbacks are able to flap and rotate their flippers in a manner similar to California sea lions. Humpbacks rest at the surface with their bodies lying horizontally. They frequent shallow seamounts, commonly exploring depths of up to 80 meters (260 ft) and occasionally diving as deep as 616 meters (2,021 ft).

These deeper descents are believed to serve various purposes, including navigational guidance, communication with fellow humpback whales, and facilitation of feeding activities. Dives typically do not exceed five minutes during the summer but are normally 15–20 minutes during the winter. As it dives, a humpback typically raises its tail fluke, exposing the underside. Humpbacks have been observed to produce oral “bubble clouds” when near another individual, possibly in the context of “aggression, mate attraction, or play”.

Humpbacks may also use bubble clouds as “smoke screens” to escape from predators. Humpback whales feed from spring to fall. They are generalist feeders; their main food items are krill, copepods, other plankton, and small schooling fish. The most common krill species eaten in the southern hemisphere is the Antarctic krill. Farther north, the northern krill and various species of Euphausia and Thysanoessa are consumed.

Fish prey include herring, capelin, sand lances, and Atlantic mackerel. Like other rorquals, humpbacks are “gulp feeders”, swallowing prey in bulk, while right whales and bowhead whales are skimmers. The whale increases its mouth gape by expanding the grooves. Water is pushed out through the baleen. In the southern hemisphere, humpbacks have been recorded foraging in large, compact gatherings numbering up to 200 individuals.

A study undertaken in May 2009 found a super-aggregation of krill in Wilhelmina Bay, on the west side of the Antarctic Peninsula, with a large number of humpback whales feeding on the krill. Researchers counted a density of 5.1 whales per square kilometer. Smaller and less dense aggregations of krill and whales were also found in Andvord Bay to the south. Krill and humpback whales are abundant in late autumn along the western Antarctic Peninsula, particularly in Wilhelmina Bay, where the whales seem to eat as much as possible in preparation for the winter.

Humpbacks typically hunt their prey with bubble nets, which is considered to be a form of tool use. Bubble-net feeding allows whales to consume more food per mouthful while using less energy; it is particularly useful for low-density prey patches. A group swims in a shrinking circle while blowing air from their blowholes, capturing prey above in a cylinder of bubbles. They may dive up to 20 m (70 ft) while performing this technique. Bubble-netting comes in two main forms: upward spirals and double loops.

Upward spirals involve the whales blowing air from their blowholes continuously as they circle towards the surface, creating a spiral of bubbles. Double loops consist of a deep, long loop of bubbles that herds the prey, followed by slapping the surface and then a smaller loop of bubbles that precedes the final capture. Combinations of spiraling and looping have been recorded. After the humpbacks create the “nets”, the whales swim into them with their mouths gaping and ready to swallow. Bubble-net feeding has also been observed in solitary humpbacks.

Using network-based diffusion analysis, one study argued that whales learned lobtailing from other whales in their group over 27 years in response to a change in primary prey. The tubercles on the flippers stall the angle of attack, which both maximizes lift and minimizes drag (see tubercle effect). This, along with the shape of the flippers, allows the whales to make the abrupt turns necessary during bubble-feeding.

At Stellwagen Bank off the coast of Massachusetts, humpback whales have been recorded foraging at the seafloor for sand lances. This involves the whales flushing out the fish by brushing their jaws against the bottom. Humpback whales often have barnacles living on their skin, the most common being the acorn barnacle species Coronula diadema and Coronula reginae, which in turn are sites for attachment for goose barnacle species like Conchoderma auritum and Conchoderma virgatum.

They are most abundant at the lower jaw tip, along the middle ventral groove, near the genital slit, and between the bumps on the flippers. C. reginae digs deep into the skin, while attachments by C. diadema are more superficial. The size of the latter species provides more sites for attachment by other barnacles. Barnacles are considered to be epibionts rather than parasites, as they do not feed on the whales, though they can affect their swimming by increasing drag.

The whale louse species Cyamus boopis is specialized for feeding on humpback whales and is the only species in its family found on them.^[67] Internal parasites of humpbacks include protozoans of the genus Entamoeba, tapeworms of the family Diphyllobothriidae, and roundworms of the infraorder Ascaridomorpha. Saxitoxin, a paralytic shellfish poisoning from contaminated mackerel, has been implicated in humpback whale deaths

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