In which scripture it is written that there are 84 Lakh types of organisms? Who was the person who said it? Is it written in Gita? Was it said by god?
It is from the Skanda Purana, 3:2:8:26-29:
Now, dear son, create duly nether worlds, earth, rivers, seas and forests in the Cosmic Sphere. The following too should be created: trees, mountains, bipeds, animals, birds, Gandharvas, Siddhas, Yakṣas, Rākṣasas, beasts of prey and all those living beings of eight million and four hundred thousand species. They are to be of four different types, each consisting of two million and one hundred thousand species. They are: (1) Udbhijjas or species of vegetation that grow breaking up the surface of the earth; (2) Svedajas or sweat-born ones such as insects, worms etc.; (3) Jarāyujas (viviparous beings) and (4) Aṇḍajas (oviparous beings). You create all these things quickly.”
The person speaking is Sri Vishnu.
Here is the Sanskrit version:
putra tvaṃ vidhinā cādya kuru brahmāṃḍagolake |
pātālaṃ bhūtalaṃ caiva siṃdhusāgarakānanam || 26 ||
vṛkṣāśca girayo dvipadāḥ paśavastathā |
pakṣiṇaścaiva gaṃdharvāḥ siddhā yakṣāśca rākṣasāḥ || 27 ||
śvāpadādyāśca ye jīvāścaturāśītiyonayaḥ |
udbhijjāḥ svedajāścaiva jarāyujāstathāṃḍajāḥ || 28 ||
ekaviṃśatilakṣāṇi ekaikasya ca yonayaḥ |
kuru tvaṃ sakalaṃ cāśu ityuktvāṃtaradhīyata |
brahmaṇā nirmitaṃ sarvaṃ brahmāṃḍaṃ ca yathoditam || 29 ||
I will try to see if it is in the Gita, too, but it is definitely in the Skanda Purana.
It is also in Garuda Purana.
Number of births and importance of human birth
In the eighty four lacs of bodies of creatures one does not acquire true knowledge anywhere unless one is born as a man.
Here, after thousands of crores of births a creature obtains human form only sometime due to aggregate of virtue.
Having obtained a rare human form he should endeavour for moksha. If he does not endeavour for it, there can be no greater sinner in the world.
Born in the most beautiful human form he incurs the sin of slaying a Brahmin if he neglects his self.
Without human body it is not possible to obtain the supreme goal. One should be, therefore, very cautious to guard wealth in the form of his body and perform good actions. …… So far as this body remains intact he should practice dharma. One is a perfect fool who digs a well only when the house is on fire.
[Garuda Purana, Dharma Khanda, Chapter XLIX]