As stated previously, the species seeded on Gaia are either domestic, invasive, urban, or in some other way tied to humans (aside from a few invertebrates).
Domestic dog (of various breeds)
Domestic cat
Domestic pig
Brown rat
Guinea pig
Common Raccoons
Goats
Red fox
Cottontail rabbit
Grey squirrel
Northern Brown bandicoot
Sugar glider
Llama
Ferret
Virginia opossum
Southern red-backed vole
Koi
Beta fish
Pacostymus
Oscar/velvet cichlid
Common molly
Gobis
Mosquitofish
Mandarinfish
Silver Carp
Northern Snakehead
Rainbow Trout
Clownfish
Striped sea bass
Salmon
Tilapia (5 species)
European Bass
Milkfish
Red drum
Sea Lamprey
Blue jays
Chickens
Canada Geese
Domestic Turkeys
House sparrows
Rock Doves
Peregrine Falcons
Seagulls
Zebra finch
Budgie
Cockatiel
Starlings
Peafowl
Garter snakes (5 species)
Red-eared slider turtle
Common Snapping turtle
Brown Anole
Bearded dragon
Green iguana
Cane toad
Tiger salamander
American bullfrog
Cockroaches (American)
Mealworms
Asian giant hornets
Honeybees
Earwigs
Gypsy moth
Tree wetas
Hercules beetle
House Cricket
Housefly
West Indian drywood Termites
Gray silverfish
Red imported Fire ants
Linne's Cicadas
House centipede
Whip spider (Phrynus longipes)
Camel spider (+10 species)
Giant Vinegaroon
House spider
Carolina Wolf spider
Ecuadoran Hermit crabs
European Crayfish
Brine shrimp
Common Pillbug
Acorn barnacle
Earth worms (Nightcrawler and Red wiggler)
European medicinal leech
Christmas tree worm
European Fanworms
Banana slug
Common Cuttlefish
Cone Snail (20+ species)
Zebra Mussels
Queen Scallops
Garden Snail
Sea Anemones (10+ species)
Sea Urchins (20+ species)
Sea Cucumbers (40+ species
Purple Seastar
Various algae
Common latans
Kudzu
Papyrus
Aloa Vera
Maze
Wheat
Sunflower
Carrot
Potato
Yam
Wild Bananas
Apples
Pears
Cantaloupe
Watermelon
Grapes
Roses
Ginko biloba
Cedar
Indigo
Henna Tree
Kentucky bluegrass
Nori seaweed
Various fungi, bacteria and other single celled organisms have also been seeded on Gaia for the purposes of filling out the ecosystems of the planet and allowing biological processes to occur.