Śrīmad-Bhāgavatam · Text 2.10.29
Who is speaking and story frame
आदित्सोरन्नपानानामासन् कुक्ष्यन्त्रनाडय: ।
नद्य: समुद्राश्च तयोस्तुष्टि: पुष्टिस्तदाश्रये ॥ २९ ॥
āditsor anna-pānānām
āsan kukṣy-antra-nāḍayaḥ
nadyaḥ samudrāś ca tayos
tuṣṭiḥ puṣṭis tad-āśraye
When there was a desire to have food and drink, the abdomen and the intestines and also the arteries became manifested. The rivers and seas are the source of their sustenance and metabolism.
Read Śrīla Prabhupāda's purport on Vedabase.io