---
title: "What the sources say about the Swordfish | AnimalTracks.wiki"
description: "36 claims from the Swordfish profile, each beside the words of the source that backs it."
image: "https://animaltracks.wiki/images/animals/swordfish-1.webp"
canonical: "https://animaltracks.wiki/animals/swordfish/sources/"
---

# What the sources say about the Swordfish (*Xiphias gladius*)

> 36 claims from the Swordfish profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Swordfish](https://animaltracks.wiki/animals/swordfish/)

## Collette et al. (2022). Xiphias gladius. The IUCN Red List of Threatened Species 2022: e.T23148A46625751.

https://doi.org/10.2305/iucn.uk.2022-1.rlts.t23148a46625751.en

| The page says | The source says |
| :--- | :--- |
| The IUCN Red List rates the swordfish Near Threatened | IUCN Red List category: Near Threatened (NT). |
| Near Threatened | IUCN Red List category: Near Threatened (NT). |

## Swordfish (Xiphias gladius). Florida Museum of Natural History, Discover Fishes.

https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/xiphias-gladius/

| The page says | The source says |
| :--- | :--- |
| Swordfish are believed to swim down to 2,100 feet (650 m) or deeper, where the water may be just above freezing | it is believed to swim to depths of 2,100 feet (650 m) or greater, where the water temperature may be just above freezing |
| a large bundle of tissue associated with one of the eye muscles | a “brain heater,” a large bundle of tissue associated with one of the eye muscles, which insulates and warms the brain |
| A female swordfish may carry from 1 million to 29 million eggs, and estimates vary a lot | Estimates vary considerably, but females may carry from 1 million to 29 million eggs in their gonads |
| The bill is long, even for a billfish | The bill is long relative to other billfishes |
| Adults have no teeth and no scales | Adults lack scales and teeth |
| Young swordfish have scales, but they lose them by about 3 feet (1 m) long | While the young have scales, these are lost by the time the fish attain a body length of about 3 feet (1 m) |
| Swordfish feed mostly on pelagic fishes (fish of the open sea) and occasionally on squid | They feed mostly upon pelagic fishes, and occasionally squids and other cephalopods |
| Squid and cuttlefish pulled from swordfish stomachs often carry slashes | squid and cuttlefishes commonly exhibit slashes to the body when taken from swordfish stomachs |
| in one study most large fish prey had been slashed, while small prey were eaten whole | A recent study found the majority of large fish prey had been slashed, while small prey items had been consumed whole |
| Swordfish reach a maximum of 177 inches (455 cm) and 1,400 pounds (650 kg) | Swordfish reach a maximum size of 177 in. (455 cm) total length and a maximum weight of 1,400 lbs. (650 kg) |
| Nearly all of those over 300 pounds (140 kg) are female | nearly all specimens over 300 lbs. (140 kg) are female |
| Swordfish live in the Atlantic, Pacific and Indian Oceans, from about 60 degrees north to 45 degrees south | found in oceanic regions worldwide, including the Atlantic, Pacific, and Indian Oceans ... with a latitudinal range of approximately 60°N to 45°S |
| They migrate, generally moving to warmer water in winter and cooler water in summer | highly migratory species, generally moving to warmer waters in the winter and cooler waters in the summer |
| they often turn up in frontal zones, where ocean currents collide and productivity is high | It is often present in frontal zones, areas where ocean currents collide and productivity is high |
| Yes. Of all the billfish, the swordfish has the widest temperature tolerance, and it turns up in water from 41 to 80 degrees F (5 to 27 degrees C) | the swordfish has the widest temperature tolerance of any billfish, and can be found in waters from 41-80°F (5-27°C) |
| It is mainly a warm-water fish, but its brain heater helps it swim in cold depths | Although mainly a warm-water species ... One adaptation which allows for swimming in such cold water is the presence of a “brain heater,” |
| Open oceans worldwide, in tropical, temperate and sometimes cold waters | found in oceanic regions worldwide ... It is found in tropical, temperate, and sometimes cold waters |
| Mostly pelagic fish, and some squid | They feed mostly upon pelagic fishes, and occasionally squids and other cephalopods |
| A fish with a heater for its brain and a flattened bill it apparently uses to slash prey | a “brain heater,” a large bundle of tissue associated with one of the eye muscles ... appears as a flattened oval in cross section ... The sword is apparently used in obtaining prey, as squid and cuttlefishes commonly exhibit slashes to the body |
| in cross section it appears as a flattened oval | its prolonged “bill”, which appears as a flattened oval in cross section |
| Predators of adult swordfish include killer whales | Predators of adult swordfish include marine mammals such as killer whales |
| Swordfish also host 49 species of parasites, from tapeworms in the gut to flukes on the gills | Swordfish are hosts to 49 species of parasites including cestodes (tapeworms) in the stomach and intestines, nematodes (roundworms) in the stomach, tremodes (flukes) on the gills |
| One adaptation that lets them swim in such cold water is a "brain heater" | One adaptation which allows for swimming in such cold water is the presence of a “brain heater,” |
| The sword is apparently used to catch prey | The sword is apparently used in obtaining prey |
| one adaptation that lets it swim in depths where the water may be just above freezing | where the water temperature may be just above freezing. One adaptation which allows for swimming in such cold water is the presence of a “brain heater,” |

## North Atlantic Swordfish. NOAA Fisheries.

https://www.fisheries.noaa.gov/species/north-atlantic-swordfish

| The page says | The source says |
| :--- | :--- |
| The ones caught by the North Atlantic fishery average 50 to 200 pounds | the average size caught in the fishery is 50 to 200 pounds |
| NOAA says North Atlantic swordfish live about 9 years | Swordfish live about 9 years |
| NOAA calls Atlantic swordfish one of the fastest predators in the ocean and says their streamlined bodies let them swim at speeds of up to 50 mph | Atlantic swordfish are one of the fastest predators in the ocean. Their streamlined body allows them to swim at high speeds, up to 50 mph |
| Females there can reproduce between 4 and 5 years of age | Females are able to reproduce between 4 and 5 years of age |

## Fritsches, Brill & Warrant (2005). Warm eyes provide superior vision in swordfishes. Current Biology.

https://doi.org/10.1016/j.cub.2004.12.064

| The page says | The source says |
| :--- | :--- |
| It warms the eyes and brain up to 10 to 15 degrees C above the water around them | a highly specialized heating system located in an extraocular muscle specifically warms the eyes and brain up to 10 degrees C-15 degrees C above ambient water temperatures |
| in fast-swimming predatory fish such as the swordfish, warming the retina improves temporal resolution, and so the detection of rapid motion | warming the retina significantly improves temporal resolution, and hence the detection of rapid motion, in fast-swimming predatory fishes such as the swordfish |
| Depending on dive depth, it can be more than ten times higher in these fish than in fishes whose eyes match the water temperature | Depending on diving depth, temporal resolution can be more than ten times greater in these fishes than in fishes with eyes at the same temperature as the surrounding water |
| A heating tissue in one of its eye muscles that warms the brain and eyes up to 10 to 15 degrees C above the water | a highly specialized heating system located in an extraocular muscle specifically warms the eyes and brain up to 10 degrees C-15 degrees C above ambient water temperatures |
| A swordfish's warmed eyes can resolve rapid motion more than ten times better than fish eyes at water temperature, depending on dive depth. | Depending on diving depth, temporal resolution can be more than ten times greater in these fishes than in fishes with eyes at the same temperature as the surrounding water (note: vibe.reason) |