---
title: "Sei Whale"
description: "Balaenoptera borealis — Mammiferi. The sei whale ( SAY; Balaenoptera borealis) is a baleen whale."
canonical: https://animalchecklist.com/it/animal/sei-whale
last_updated: 2026-09-20
---

# Sei Whale

> Balaenoptera borealis — Mammiferi. The sei whale ( SAY; Balaenoptera borealis) is a baleen whale.

- Scientific name: *Balaenoptera borealis*
- Category: `mammals` (Mammiferi)
- Habitats: `sea` (Mare e costa)
- iNaturalist observations: 987
- Wikidata: [Q185097](https://www.wikidata.org/wiki/Q185097)
- iNaturalist taxon: [41559](https://www.inaturalist.org/taxa/41559)

## Names

- en: Sei Whale
- de: Seiwal
- es: Ballena de Sei
- fr: Rorqual boréal
- nl: Noordse vinvis
- pt: Baleia-sei
- pl: Płetwal czerniakowy

## Countries with the most observations

CL (153), AR (136), PT (50), FK (25), AU (9), DK (5), NZ (3)

## Summary

The sei whale ( SAY; Balaenoptera borealis) is a baleen whale. It is one of ten rorqual species, and the third-largest member after the blue and fin whales. It can grow to 19.5 m (64 ft) in length and weigh as much as 28 t (28 long tons; 31 short tons). Two subspecies are recognized: B. b. borealis and B. b. schlegelii. The whale's ventral surface has sporadic markings ranging from light grey to white, and its body is usually dark steel grey in colour. It is among the fastest of all cetaceans, and can reach speeds of up to 50–55 km/h (31–34 mph) over short distances. 
It inhabits most oceans and adjoining seas, and…

Text: Wikipedia (en), CC BY-SA 4.0 — https://en.wikipedia.org/wiki/Sei_whale

## Photo

![Sei Whale](https://animalchecklist.com/img/animals/sei-whale/medium.jpg)

Photo: Federico Muñoz · CC0 · inaturalist — https://www.inaturalist.org/observations/252765353

## Machine access

`GET https://animalchecklist.com/api/v1/animals/sei-whale?lang=it` — see [openapi.json](https://animalchecklist.com/openapi.json).