Adult common seadragons are a reddish colour, with yellow and purple striped markings; they have small, leaf-like appendages that resemble kelp or seaweed fronds, providing camouflage, as well as a number of short spines for protection.

[3][4] As with seahorses and the other syngnathids, the seadragon has a similarly tubular snout and a fused, toothless jaw into which it captures small invertebrate prey at lightning speed.

They lack the prehensile tail that many seahorses and pipefishes have evolved as anchors, to clasp and steady themselves; seadragons, instead, drift in the water among kelp and seaweed masses, which they blend-into with their leafy-looking appendages.

[13] In July of the same year, Monterey Bay Aquarium, on California's central coast, successfully bred and hatched-out common seadragons, on-exhibit.

[14] Most recently, Birch Aquarium (in La Jolla, San Diego, California) successfully bred and hatched common seadragon fry in early 2023.

This species is not at present a victim of bycatch or a target of trade in traditional Chinese medicine, two activities which are currently a threat to many related seahorse and pipefish populations.

[17][18] More recent research suggests that the weedy seadragon may be far more endangered than initially assumed as a result of climate change-induced marine heatwaves on the Great Southern Reef.

[4] Monitoring of populations may provide indications of local water quality and seadragons could also become an important 'flagship' species for the often-overlooked richness of the unique flora and fauna of Australia's south coast.

[25] In the November 2006 issue of National Geographic magazine, marine biologist Greg Rouse is reported as investigating the DNA variation of the two seadragon species across their ranges.