The plural for "shrimp" works much like the plural for "fish" does in Standard American English. In this case, the standard correct answer should be "The shrimp are orange."
Of course both should be accepted. Though, I do grimace every time I hear someone say "shrimps" when referring to a menu item. Rather, what I am proposing is that the suggested correct or top translation should appear as "shrimp". Also, I believe the typical usage of "shrimps" is to refer to multiple species of shrimp/s. Similar to the plural of fish – "fish" vs. "fishes".
I prefer "shrimp" for the plural form as well, but unlike fish, the plural of "shrimp" really can be "shrimps", even among the same species. This is likely a regional variation in English.
"shrimp" is a complicated word! Here are its attributes from Wiktionary:
shrimp (countable and uncountable, plural shrimp or shrimps)
Plural "fishes" only refers to species, whereas plural "shrimps" can refer to species or individuals. It's your choice whether you use "shrimp" or "shrimps" for multiple individuals.
"Les crevettes sont oranges." marked incorrect
Certain colour adjectives are invariable—that is, they never change regardless of the gender and number of the noun. All of these adjectives are derived from nouns. Take orange for example.
As in English, in French orange refers to both the colour and the fruit (une orange). Though you can certainly have de multiples oranges (multiple oranges), the adjective form of the word never changes, even in the plural:
J'ai acheté des chaussures orange.
"I bought orange shoes."
You can find a list of them here:
In Australia, shrimp are called prawns. Can prawns be accepted please?
Prawns is an accepted answer, provided the rest of the sentence is correct.
Correct, orange does not form agreements with the noun.
Color adjectives that come from animals, fruits, flowers, gems, or other nouns found in nature are usually invariable and don't form agreements with the noun.
Marron, orange, and or are common invariable color adjectives. For more, you can check out this list.