How many types of sea stars are there in the world?

there are about 35 different species:

Seahorse - Facts & Links - NamesSeahorse Names

Types of Seahorses ~ SCIENTIFIC NAME / COMMON NAME

Hippocampus abdominalis - Big Belly Sea Horse

Hippocampus aimei - Freshwater Sea Horse

Hippocampus algiricus - West African Sea Horse

Hippocampus angustus - Western Australian Sea Horse or Narrow-bellied Sea Horse

Hippocampus antiquorum -

Hippocampus barbouri - Barbour's Sea Horse

Hippocampus bargibanti - Bargibant's Sea Horse or Pygmy Sea Horse

Hippocampus borboniensis - Réunion Sea Horse

Hippocampus breviceps - Short-snouted Sea Horse or Short-head Sea Horse

Hippocampus brevirostris - Short-snouted Sea Horse or Short-nosed Sea Horse

Hippocampus camelopardalis - Giraffe Sea Horse

Hippocampus capensis - Spinach pipefish or Knysna Sea Horse

Hippocampus comes - Tiger tail Sea Horse

Hippocampus coronatus - Japanese Sea Horse or Red and Black Sea Horse

Hippocampus dahli - Synonym for Hippocampus planifrons

Hippocampus Denise - Denise's pygmy seahorse

Hippocampus erectus - Atlantic Lined Sea Horse or Northern Sea Horse

Hippocampus fisheri - Fisher's Sea Horse

Hippocampus fuscus - Black Sea Horse or Sea pony

Hippocampus guttulatus - Long-snouted Sea Horse

Hippocampus heptagonus - Synonym for Hippocampus erectus

Hippocampus hilonis - Synonym for Hippocampus kuda

Hippocampus hippocampus - Short-snouted Sea Horse

Hippocampus histrix - Yellow Sea Horse or Thorny Sea Horse

Hippocampus hudsonius - Synonym for Hippocampus erectus

Hippocampus hunsonius punctulatus - Synonym for Hippocampus erectus

Hippocampus ingens - Pacific Sea Horse or California Sea Horse

Hippocampus jayakari - Jayakar's Sea Horse

Hippocampus kelloggi - Great Sea Horse

Hippocampus kuda - Oceanic Sea Horse or Kellogg's Sea Horse or Common Sea Horse or Yellow Sea Horse or Spotted Sea Horse

Hippocampus laevicaudatus - Synonym for Hippocampus erectus

Hippocampus lenis - Synonym for Hippocampus planifrons

Hippocampus lichtensteinii - Lichtenstein's Sea Horse

Hippocampus melanospilos - Synonym for Hippocampus kuda

Hippocampus minotaur - Bullneck Sea Horse

Hippocampus mohnikei - Japanese Sea Horse

Hippocampus moluccensis - Synonym for Hippocampus kuda

Hippocampus novae-hollandiae - Synonym for Hippocampus whitei

Hippocampus obtusus -

Hippocampus planifrons - Dahl's Sea Horse

Hippocampus polytaenia - Synonym for Hippocampus kuda

Hippocampus punctulatus - Synonym for Hippocampus erectus

Hippocampus ramulosus - Mediterranean Sea Horse

Hippocampus regulus -

Hippocampus reidi - Brazillian Sea Horse

Hippocampus rhynchomacer - Synonym for Hippocampus kuda

Hippocampus sindonis - Dhiho's Sea Horse

Hippocampus spinosissimus - Hedgehog Sea Horse

Hippocampus subelongatus - West Australian Sea Horse

Hippocampus taeniopterus - Synonym for Hippocampus kuda

Hippocampus takakurae - Tanaka Threespot Sea Horse

Hippocampus trimaculatus - Longnose Sea Horse

Hippocampus tristis - Sad Sea Horse

Hippocampus whitei - Crowned Sea Horse or Sydney Sea Horse or New Holland Sea Horse or White's Sea Horse

Hippocampus zosterae - Dwarf Sea Horse