Makara means a crocodile or a shark. It might also mean a giant mythical being which carries Ganga devi. Also it is a constellation i nastrology which is the shape of a crocodile. Hence the name.
The word "Makara" is not only used in the Itihasa Mahabharata, it is used in Ramayana several times to indicate crocodiles and sharks.
तन् नक्र मकर आकीर्णम् तिमिम्गिल झष आकुलम् |
वायु वेग समाधूतम् पन्नगैर् इव सागरम् || ५-९-७
That building surrounded by the wives of Ravana, by demonesses, and princesses brought by strength, was like an ocean filled with crocodiles, big fishes, sharks and other fishes, moved by the speed of wind, and together with serpents.
Here, nakra can also mean an alligator or a crocodile (According to Monier- williams dictionary 1899).
In the Yuddhakanda chapter 21 where Sri Rama aims Brahmastra towards the ocean god, makara is mentioned.
अद्य मद् बाण निर्भिन्नैर् मकरैर् मकर आलयम् |
निरुद्ध तोयम् सौमित्रे प्लवद्भिः पश्य सर्वतः || ६-२१-१७ (6.21.17)
"O, Lakshmana! Behold now this ocean, having its water made suffocated soon with its crocodiles floated on all sides and broken asunder by my arrows".
Sometimes this is identified with a shark. In Bhagavad Gita, Krishna says, He is the shark among the fishes.
pavanaḥ pavatām asmi rāmaḥ śastra-bhṛtām aham
jhaṣāṇāṁ makaraś cāsmi srotasām asmi jāhnavī
Of moving things, I am the wind. Among warriors I am Rama; among fishes, I am the shark, and amongst rivers, I am Ganga.
Sometimes Makara is identified as a mythological creature which is the vehicle of Ganga devi.
In addition to Makara, other creatures like Timi, Timingala, Jhasha, Śiśumāra are also mentioned. Jhasha, Timi, Timingala are already mentioned in the question. Jhasha is a fish. Timi is a type of fabulous fish like a whale. These type of fishes are mentioned in Harivamsa too. Timingala is a huge whale.
Śiśumāra is a porpoise which is the carrier of Varuna, the sea god. This is mentioned in the Vamana Purana chapter 9
रूद्र कर्णम्लोद्भातः श्यामो जलधिसंज्ञकमः |
शिशुमारो दिव्यगतिः वाहनं वरुणस्य चा ||16||
Śiśumāra called jaladhi is the carriage of Varuna. It was originated from the ear wax of Rudra. It has dark complexion and divine speed.
Some Rakshasa soldiers rode on these porpoises. There is a mention of it in the Uttara Kanda of Ramayana.
And all the Rakshasas went covering the sky, some on asses, some on camels, some on horses, some on quick-coursing porpoises and some on huge serpents. And beholding Ravana proceed, hundreds of Daityas, inimical to the celestials, followed him. Having arrived at the city of Madhu and entered there the ten-necked demon did not behold Madhu but espied his sister.
When we take the context of the Mahabharata verse you quoted, the word Makara can mean a crocodile or a shark.