Demand for yet another Dr. Dolittle movie is admittedly low, but the fun, funny, and visually rich Dolittle justifies its existence to a surprising degree.

Directed by Stephen Gaghan (Syriana; Gold), the family-friendly period adventure gets off to a strong start with beautiful opening animation that, on its own, would be an Academy Award nominee for Best Animated Short Film.

The sequence efficiently sets up Dr. John Dolittle (Robert Downey Jr.), his rise to prominence as a veterinarian who can speak to animals, and his descent into seclusion. The economic storytelling continues in establishing the conflict that pulls him back into society — one involving a deathly ill queen (Jessie Buckley, Wild Rose), a nefarious plot to usurp the throne, and the threat of him losing his home if she croaks.

Though the arc of tween Tommy Stubbins (Harry Collett, Dunkirk) as a reluctant Dr. Dolittle’s apprentice, tagging along on the perilous voyage to obtain a mythical antidote, is a weak addition, it works as a means of shaking the vet from his hermit ways and more firmly reconnecting him with the human world.

In that relationship and elsewhere, Dolittle appears headed toward disaster, but saves face nearly every time. Never is this threat more apparent than in the film’s depiction of Dr. Dolittle communicating with a range of animals in their own languages. Rather than sticking with subtitled grunts and clicks and hoots — a mind-numbing proposition — Gaghan quickly shifts to fully-English cross-species communications and never looks back, allowing the film’s humor, thrills, and slick CGI to take full control.

After months of seeing shoddy animal special effects in the film’s trailers, the final products are shockingly polished and elevated by a Who’s Who of vocal talent, each of whom earn their share of laughs. Emma Thompson classes up the joint as parrot narrator Poly and Craig Robinson is a riot as a revenge-minded squirrel Kevin, but Jason Mantzoukas is arguably the funniest of the bunch as clumsy, lovesick dragonfly James, who’s tasked with missions beyond his capabilities, yet performs admirably.

Furthermore, Kumail Nanjiani atones for his previous voicing of an animated entity — the miserable Men in Black: International — as neurotic ostrich Plimpton, while cheeky human turns by Jim Broadbent, Michael Sheen, and Antonio Banderas fortify the film’s flesh-and-blood legitimacy.

With the above creatures and more operating in comic harmony, the main weakness plaguing Gaghan’s script with How I Met Your Mother writers Dan Gregor and Doug Mand is an excess of potty humor — but it’s a PG-rated family film with talking animals, so butt/fart jokes are to be expected.

Still, for every blocked colon there’s a hilarious, rattled octopus witness who squeaks, “Snitches get stitches,” making the juvenile yuks easily forgivable.

Grade: B. Rated PG. Now playing at AMC Classic, Biltmore Grande, and Carolina Cinemark

(Photo: Universal Pictures)