Shiva's consort, Durga (Parvathi, Uma, Chandi and Kali), uses a lion as her vehicle. The lion represents her heroic prowess. As she rides on the lion to trample down Mahisasura, she represents the subduer of vices. Durga is often shown placed between Laksmi and Sarasvati, representing mundane opulence and mundane knowledge.
Saraswati rides Hamsa the Swam, or sometimes a peacock. The swan is a symbol of spiritual purity, and those who have transcended the material nature are sometimes called supreme swans, or "paramaharnsa".
Lakshmi rides on an owl named Uluka. Uluka, which means 'owl' in Sanskrit, is also one of the names of lndra, the king of the demigods, who personifies wealth, power and glory. Thus, Lakshmi, the goddess of fortune, rides on a fitting carrier. The comparison of Indra's glory to a partially blind bird speaks to the difference between material and spiritual wealth, as Lakshmi is the goddess of spiritual wisdom.
Saraswati on Hamsa and Lakshmi with Uluka