A Risso’s dolphin caught up in fishing line. Dolphin numbers in the Indian Ocean may have dropped by more than 80% in recent decades, with an estimated 4 million small cetaceans caught as “by-catch” in commercial tuna fishing nets since 1950, according to a study
A comparison of the skulls of two fish-eating #southernresidentkillerwhales at #thewhalemuseum in Friday harbor. Top: L8, a large bull who died in 1977; Bottom: L112, a three year old calf who died in 2012. #orca #killerwhale #skull #bones #odontoceti (at The Whale Museum) https://www.instagram.com/p/BoIAyJsA1wM/?utm_source=ig_tumblr_share&igshid=1op0vjo10kv0h
A comparison of the skulls of two fish-eating #southernresidentkillerwhales at #thewhalemuseum in Friday harbor. Top: L8, a large bull who died in 1977; Bottom: L112, a three year old calf who died in 2012. #orca #killerwhale #skull #bones #odontoceti (at The Whale Museum) https://www.instagram.com/p/BoIAyJsA1wM/?utm_source=ig_tumblr_share&igshid=8ctzra1bghl1
Modernbeluga whalesandnarwhals are the only living representatives of the monodontid lineage, found only in cold Arctic and sub-Arctic waters. But this whale family actually first evolved in much warmer climates – and some of them were downright tropical.
It seems to have had a larger number of functional teeth than modern monodontids, and probably didn’t suction feed like its modern close relatives. Instead it may have fed more like most porpoises and dolphins, relying more on speed and snapping jaws to capture prey.
It inhabited the Mediterranean at a time not long after the sea there had mostly dried up and then been rapidly refilled. The presence of warm-water marine species such as bull sharks,tiger sharks, and dugongs in the same fossil beds as Casatia indicates the local climate at the time was hotter than it is today, with tropical temperatures – and suggests that this whale’s ancestors must have originally moved into the replenishing Mediterranean from lower latitudes alongside these other warmth-adapted animals.
This tropical monodontid was also much closer related to modern belugas than modern narwhals are, which raises the possibility that the two living monodontid species actually specialized for colder conditions completely independently of each other rather than descending from a cold-adapted common ancestor. Instead modern belugas and narwhals may have originated from separate warm-water monodontid ancestors who evolved similar cold-tolerant adaptations in parallel as the climate cooled during the onset of the Quaternary ice age, while the rest of their relatives all went extinct.
MICROPLASTICS IN THE GASTROINTESTINAL TRACTS OF ALL BELUGA EXAMINED FROM ARCTIC WATERS
According to a recent published study in Marine Pollution Bulletin, researchers worked with community-based monitors and Inuvialuit hunters from Tuktoyaktuk (Northwest Territories, Canada) to sample seven beluga whales in 2017 and 2018.Microplasticswere detected in the gastrointestinal tracts in every individual beluga whale, with each whale having an average of nearly 97 particles, but some of them had 147 particles.
Microplastics are plastic fragments, regularly smaller than 5 mm in size, and represent an emerging global environmental concern, as they have been detected in multiple aquatic species. However, very little is known about the presence of microplastics in higher trophic species, including cetaceans.
-Examples of microplastic particles observed within beluga gastrointestinal tracts (left: polystyrene fragment; right: polyester fibre) Bar is 0.02 cm.
Researchers do not know how microplastics enter whales, but they believe is because whales feed on fish, which have already ingested plastic.