Animal vs. Male Anatomy

I know this is gonna sound like "typical Morbus funny ha ha" stuff, but I've got a serious question, spurned on by a rather unserious picture of a gigantic whale penis. I've pasted a chatlog, with some names changed in respect to their oogleability:

<male_1> wooohooo!!
<male_1> OMG
<SteamedPenguin> lol
<male_1> yet another reason i didn't go into cetacean biology
<female_1> omg
<female_1> well, it's proportionate
<female_1> the whale looks happy
<male_1> lol
<SteamedPenguin> wouldn't you be happy?
<SteamedPenguin> swimming pool, sun, and somebody stroking you
<Morbus> on a serious note, why do penis' look the same on animals, yet I know of little female-like-breasts? are there animals that have breasts like a woman?
<male_1> not sure i can answer that, different tissues and all, maybe a cow udder is the closest analogue i can think of ATM
<Morbus> i find it remarkable that a whale has a penis just like mine. but that female whales don't have breasts like a woman.
<male_1> lmao
<Morbus> ok, yeah, i know that sounded weird. but i'm serious!
<male_1> functional evolution perhaps, they'd cause unnecessary drag in the water. not that they used to have external breasts and they evolved away, i don't mean that
<SteamedPenguin> a penis has that wonderful hydrodynamic shape
<Morbus> yeah, but... hmm, yeah, i suppose a penis would float up to the body, thus reducing drag.
<male_1> samir - they retract, they aren't out there causing drag
<Morbus> female_1: when you're swimming face down, what do your breasts do?
<male_1> lol
<Morbus> look, i know this sounds like i'm trying to be funny
<Morbus> but i'm really not.
<male_1> i know, that's what's funny :)

Thoughts? Someone told me that the whale penis probably retracts like a dog's, which would remove any issue of drag. But that still doesn't answer why there aren't human-breasted mammals running around. Do female apes have human-like breasts? What about other animals?

Update: "<male_1> another thing i thought of might be related to surface area and the blubber layer which can be literally a foot or more thick for insulation purposes, any external "danglies" would provide more surface area for potential heat loss"

Update: reports "human female breasts are secondary sexual characteristics that evolved to attract mates. According to Desmond Morris (1967), this took place along with the switch from front-to-rear to front-to-front mating, the pendulous shape and cleavage of the breasts mimicking the pre-existing attractiveness of the female buttocks. This also, according to the theory, explains why men find other pendulous shapes (like ear lobes) and other cleavages (like toes in low-vamped shoes) such a turn-on."