So why does baryon octet have the extra spin?

[Xuekai Du]

baryon decuplet and octet have same quark content, but has spin 1/2 and 3/2. So what gives octet the extra spin?

 

[mfb]

I don't think that is a meaningful question. You have two ways to combine three spin 1/2 particles to a total spin, 1/2 and 3/2. There is no "extra spin".