If the creationist model is correct, then the changes which have occurred within modern "kinds" of whales represent "microevolution", changes which are much less significant than the "macroevolution" needed to derive one group of whale from another or whales from more generalized mammals. If the intelligent design model is correct, it is not expected that ancestral whale "design" would be so nonfunctional that it would require constant reworking to make it adaptive. Some creationists have grouped whales into approximately 5 separate created kinds or "holobaramins" (Wood, 2006; Mace 2005): archaeocetes, mysticetes, sperm whales and pygmy sperm whales, beaked whales, and all other toothed whales. Many of the modifications within these lineages are far greater than those which distinguish a certain lineage from others.

Archaeocetes evolved over time and the changes which occurred within this group are certainly greater than the differences which separate them from the ancestral members of modern groups. The earliest members were 2 meters long, were capable of locomotion on land on their strong legs, and possessed unspecialized tails, unspecialized middle ears, and nostrils at the tips of their snouts. Later archaeocetes could reach 20 meters in length and were fully adapted to marine life with strong tails ending in a fluke, vestigial hind legs, nostrils positioned between the eyes (a blowhole), front flippers, and a middle ear modified for hearing underwater. If opponents of evolution can claim that animals as diverse as these could descend from a common ancestor, then there is no reason to presume that an advanced archaeocete couldn't evolve into the ancestral forms of modern whale lineages.
The skulls of modern baleen whales vary significantly.

The skulls of river dolphins and the diverse members of the group Delphinoidea vary significantly.



Extinct dolphins also varied significantly. Extinct Eurhinodelphids possessed a long, thin upper jaw which formed a spear-like snout (Slijper, 1958).

Within the Delphinoidea group, size can range from 3 feet in the Amazon river dolphin and just over 4 feet in Commerson's dolphin to 28 feet in pilot whales and 32 feet in killer whales. Among baleen whales, size varies from 35 feet (Minke whale) to 110 feet (blue whale).
Tooth number can vary from 60 in the Fransicana dolphin, 50 in the Spinner dolphin, 46 in the northern right whale dolphin, and 44 in Fraser's dolphin to 12-14 in the irrawaddy dolphin to 3-7 in Risso's dolphin, 7-11 in false killer whales, 8-10 in pilot whales, and 10-13 in killer whales. Teeth vary in shape from large and strong to small to blunted. All of the tooth buds of the fetal narwhal degenerate except for that which develops into the tusk in males which can measure 3 meters (Sylvestre, 1993; Coffey, 1977). The males of the extinct dolphin, Odobenacetops, possessed a long, walrus-like right tusk (de Muizon, 1999).

Beaked whales possess a single tooth in each lower jaw. Although sperm whales possess teeth in their upper jaws, they are vestigial and rarely break the surface of the jaw. Extinct relatives of sperm whales possessed more prominent teeth in their upper jaws. In sperm whales the two halves of the lower jaw are fused for the majority of their length (Slijper, 1958).


Baleen plates can range from about 2 feet in gray whales to 14 feet in bowhead whales. While gray whales may have 130 baleen plates, sei whales may possess 380 (Minasian, 1984; Clapham, 1997).

While many have long narrow snouts, others have essentially no snout. Separate lineages have lost their dorsal fins (such as the northern right whale dolphin and finless porpoise) and some dolphins have humped backs (Atlantic humpback dolphins). The dorsal fin may be small (irrawaddy), blunted (Hector's dolphin) or quite prominent (killer whales). The length of gestation varies from 7 months (in Dall's porpoise) to 17 months (in the northern berardius) (Sylvestre, 1993; Coffey, 1977).
White sided dolphins possess 93 vertebrae, the common dolphin 75, and the porpoise 66. Many whales lack the ability to move the majority of their vertebral columns (Slijper, 1958). Wild bottlenose dolphins have been observed to use sponges as tools in searching for food. Interestingly, those dolphins which used sponges as tools were closely related (Krutzen, 2005).

Other variations are known in closely related species. Pygmy right whales possess only four fingers while all other whales possess five (Coffey, 1977). The number of teeth decreased over time in several lineages (such as the extinct Eurhinodelphidae and Acrodelphidae) (Gaskin, 1982). Some freshwater dolphins retain primitive features such as separate neck vertebrae (Gaskin, 1982). Sperm whale intestines can measure 150 meters. While mysticetes possess a cecum and a differentiation between the large a small intestines, a cecum is absent in odontocetes and the distinction between small and large intestines is obscure (except in beaked whales) (Coffey, 1977).

While archaeocetes and dolphins possess(ed) ossified costal cartilages which join the ribs to the sternum, toothed whales have only 3-5 un-ossified cartilages, and mysticetes possess only floating ribs without connection to the sternum (Slijper, 1958).

While some who oppose evolution have separated whales into groups produced from common ancestors through "microevolution", the changes within lineages often amount to more significant differences than the "macroevolution" which separates different groups of whales.