I recently came across an article discussing Omura's whales, which I had never heard of, off the coast of Sri Lanka. I was positive I then read something saying they got up to 125 feet long, longer than Blue whales at 110 feet - but now I can't find that reference, so I'm wondering if I misread it. Does anyone know if Omura's can be bigger than Blues?
Blue whales are larger by quite a large margin so it looks like whatever you read was wrong. In fact, the Blue whale is the largest recorded mammal, and the Omura's is one of the smallest whales. Interestingly, Omura's was not established as its own breed until between 2003 and 2006. Previously it was grouped with a species that included dwarf or pygmy sized whales.
Omura's whale is among the smallest of the rorquals – only the two species of minke whale, the common and Antarctic, which reach 9.75 and 10.7 m (32.0 and 35.1 ft) in length, respectively, are smaller. Of the eight specimens taken during Japanese whaling in the Indo-Pacific, the five females ranged in length from 10.1 to 11.5 m (33.1 to 37.7 ft), while the three males ranged from 9.6 to 10.0 m (31.5 to 32.8 ft).
The blue whale (Balaenoptera musculus) is a marine mammal belonging to the baleen whale parvorder, Mysticeti. At up to 30 metres (98 ft) in length and with a maximum recorded weight of 173 tonnes (190 short tons), it is the largest animal known to have ever existed
Omura's whale is definitely smaller in length than the blue whale.
The New Bedford Whaling Museum says:
Length as an Adult: Male Omura’s whales are approximately 33 feet (10 meters) and females are about 37.7 feet (11.5 meters). This is one of the few whale species in which the females are larger than the males. (emphasis added).
Newborn blue whales are smaller than mature Omura's whales, but not by much. According to the National Marine Mammal Laboratory:
Blue whales can grow to be about 100 feet (30.5 meters) in length and may weigh around 160 tons. Newborn blue whales are about 23 feet (7 meters) long and roughly 30 tons and can add 200 pounds a day! (emphasis added.)