Browsing by Author "Suvitie, Aurelia"

Insects (Insecta) are the most species-rich class of organisms on earth. Due to their vast biodiversity, insects are found in almost every environment. However, approximately 90 % of the over 1 000 000 insect species described are terrestrial. The ocean covers over 70 % of the earths surface, but less than 2 000 marine insect species are known. The purpose of this thesis is to give the reader a comprehensive understanding of marine insect biodiversity and what has caused its sparceness in the seas. Such a multi-faceted review of the topic has not previously been written. The first aim of this review is to catalogue all insect taxons containing marine species, and to examine the habitat choices and ecology of these species. For this purpose, marine insect species have been researched using the World Register of Marine Species (WoRMS) and reference literature, as well as reviews and other articles. Based mostly on WoRMS, the number of marine insect species is determined to be 1 318, divided between 10 insect orders. In addition, seven insect orders are noted to include an unknown number of marine species. As well as examining marine insect biodiversity order-by-order, this work considers the littoral and pelagic habitats in which marine insects live, and the adaptations that are required of insects living in these environments. The second aim of this review is to investigate the lack of insects in marine environments as a phenomenon. The groundwork is laid at the beginning of the review with an examination of why and how insects have diversified so successfully. Later on, possible factors to prevent a similarily successful diversification in marine environments are presented, such as issues with osmoregulation and breathing systems, the typical features of insect reproduction and life cycles, and the fact that transitions between physically contrasting habitats are rare. Pertaining to this the evolutionary history of insects, which has produced the aforementioned features impeding radiation to the seas is also explored. Ultimately insect species in the oceans are few, because insects are a terrestrial evolutionary branch of Pancrustacea. Even though marine habits are uncommon among insects, they are not unheard of. Marine species have emerged in several insect clades and these species have adapted to their environment in numerous ways. For the purposes of further analyses and research on the radiation and biodiversity of marine insects, further surveying of the species and their habits and adaptations is recommended. This work will hopefully offer a point of reference for more detailed future studies and reviews of marine insect biodiversity and the factors that have led to the near-exclusion of insects from the seas.