On the surface level, these two species probably couldn’t be any more dissimilar. One a ferocious predator in the water, and the other as harmless as a common fly. But the way in which these two species reproduce bare interesting similarities, despite their stark visual differences.
Crocodylus acutus courtship is a seasonal event, that usually takes place in the first two months of the year. (Animal Diversity Web) [2]. The typical behaviours during this period are mostly territorial to compete for a mate and include: a number of head slaps (initiated by the female) which is often responded to with an extremely low frequency sound – “Sub Audible Vibration (SAV).” Garrick and Lang (1977) [6]. Though Animal Diversity Web [2] also adds that these behaviours include a series of loud roars and an impressive display of their teeth.
Sexual maturity is often reached between 1.8m – 2.4m, or between 8 and 10 years old. [2] (Although Alvarez del Toro (1974)[1] and Varona (1980)[15] never found a reproductive female under 2.7m.) Mating is polygynous and occurs between the months of April and May, resulting in a spawn of usually between 30 and 60 eggs [2] (Though Schmidt (1924) [12] found a litter size of 22 and Medem (1981) [9] a litter size of 105 – Both state that these instances could have been results of predation, or multiple litters in the same location.) The eggs are laid into holes dug into the ground, often 1.5m-1.8m deep, where rotting vegetation is laid on top for warmth.
Crocodylus acutus has a total of 32 chromosomes and are diploid in nature. The sex of the offspring produced through sexual reproduction is based off the temperature of the eggs during the thermosensitive period of incubation, as Crocodylus acutus lack sex chromosomes. (National Library of Medicine) [13] Temperatures below approximately 30°C and above 33°C produce females, whilst temperatures around 31.5°C produce males. (Research Gate, 2017) [10] (See figure 1)
Figure 1 – Mean incubation temperature and the resulting sex of Crocodylus acutus‘ offspring [3].
Like the Crocodylus acutus, the Quercus robur reproduces sexually, but on rare occasions can also reproduce asexually. This is known as parthenogenesis. Sexual reproduction requires the presence of another Quercus species to act as a pollen donor (International Oak Society, 2014) [7]. Quercus robur are also seasonal breeders, with fertilisation happening in the Spring and the seed maturing around October (The Conservation Volunteers, 2025) [14]. They produce around 2000 seeds, or acorns, each season – though this can vary drastically due to “masting” – one year every five where a single Quercus robur can produce in excess of 10000 acorns (Mass Audubon, 2023) [8].
However, each tree possesses both male and female flowers, though they appear at different times in order to prevent self-fertilisation. However, in rare cases it has been found that some Quercus robur have self-pollinated [5]. Male buds appear as long clusters, and appear between April and May, whereas female buds appear as red flowers that populate between the branches and leaves. (Woodland Trust, 2025) [16]. Furthermore, the Quercus robur only reach sexual maturity at 30-40 years old (Forestry England) [4]. As mentioned before, the Quercus robur can also reproduce asexually through a variety of means and processes, either naturally or artificially. Coppicing refers to when a tree is cut down, and the dormant buds that remain in the leftover stump or root collar sprout (Future Trees Trust, 2024) [5] Layering can also occur when low branches that come into contact with the ground can grow into new trees [5].
Similar to the Crocodylus acutus, the Quercus robur’s chromosomes are diploid, and has a total of 24. They also lack any sex chromosomes as all Quercus robur have both male and female flowers – this is known as being monoecious. (Sax, 1930) [11].