Most singular nouns change their spelling when they become plural.
However, some nouns look exactly the same whether they are singular or plural.
Here is a list for you to study:
one moose – two moose
I saw two moose in the field.
one deer – two deer
There were two deer in my backyard.
one shrimp – two shrimp
I ate two jumbo shrimp for dinner.
one bison – many bison
I saw many bison on the North Dakota prairie.
one reindeer – eight reindeer
The poem says Santa uses eight reindeer to pull his sleigh.
one sheep – ten sheep
One sheep was in the pasture, and another five sheep were inside the barn.
one goldfish – many goldfish
He has many goldfish in his tank.
one salmon – two salmon
Mom bought two salmon at the fish store today.
one grapefruit – three grapefruit
My neighbor gave us three grapefruit from Florida.
one series – two series
I watched one television series last summer, and I’m enjoying two television series this winter.
Most nouns add -s or -es to become plural, but some nouns look exactly the same whether they are singular or plural. You should try to memorize the list of nouns that don’t change when they become plural.