Sea-Green Northern Jumper Identification Australia

About the Sea-green northern jumper

Sea-green northern jumpers are small Australian jumping spiders best checked when an iridescent green or turquoise spider is seen on leaves, sunny walls or garden plants in Queensland. They can be confused with other Cosmophasis jumping spiders, so use location, metallic body bands, large forward-facing eyes and short jumping movement together rather than relying on colour alone.

Exact-species hero photograph: Cosmophasis thalassina by tjeales, CC BY-SA 4.0 via Wikimedia Commons.

Exact-species specimen views

These licensed exact-taxon photographs show useful anatomy and variation. Use each caption for record and image context; no single image set represents every colour, posture or habitat.

How to recognise a possible Sea-green northern jumper

Treat the metallic colour as an entry clue, not a confirmation. The World Spider Catalog accepts Cosmophasis thalassina (C. L. Koch, 1846) as the type species of Cosmophasis and gives a broad Malaysia-to-Australia distribution; Australian field use is strongest in warm Queensland settings. The Lizard Island Field Guide describes males with black bands on the carapace that stop short of the rim, unlike the very similar C. micarioides. A likely individual is a tiny salticid with the family’s large forward-facing principal eyes, a compact body and short stop-start jumps on foliage or a sunny wall. A sharp dorsal photograph can show green or turquoise metallic bands, black fields, a white front or abdominal stripe and pale leg bands, but sex, angle and light alter the pattern. Keep a routine photograph at possible Cosmophasis or possible C. thalassina unless the locality and distinguishing band boundary agree.

Clues that are not enough on their own

• Metallic green or turquoise colour treated as proof of C. thalassina
• A Queensland location used without checking the carapace band boundary
• A white abdominal stripe, pale legs or black body patch used alone
• Large forward-facing eyes used to identify a species rather than the jumping-spider family
• A short jump or still posture interpreted as a fixed behaviour
• A male colour pattern applied to a female or juvenile
• The former C. micans name or a misidentified online photograph treated as current evidence
• A garden, rainforest edge or sunny wall used as a species diagnosis
• A close crop that hides the whole body, dorsal bands and broad locality

Colour, sex and life-stage variation

The iridescent blue-green flash is structural colour and changes with viewing angle, shade and camera exposure. Males often show the strongest metallic bands; females are more variable and may look darker, browner or less saturated. Fresh moult, wear, dust and a reflective leaf can hide the black edge or make a white stripe appear yellow. Juveniles may not show the adult male pattern at all. The species has accumulated historical names and misidentifications, including C. thalassinus, C. splendens, Amycus tristriatus, Amycus splendidus and the Australian misuse of C. micans; synonymy is a taxonomic record, not a visual shortcut. Do not use one turquoise patch, a white stripe or the apparent length of a leg to separate C. thalassina from C. micarioides.

Behaviour, web and retreat

Like other jumping spiders, Cosmophasis hunts by sight rather than waiting in a capture web. It may pause on a leaf, trunk, wall or garden structure, turn toward movement with its large principal eyes and make a short jump between surfaces. A thin silk safety line or a small retreat can be present without becoming a species-level web clue. Bright sunlight can make the male’s metallic scales appear to “glow”, while a shaded individual may remain nearly black and white. Courtship, sex and age alter posture and colour, and a still spider may simply be resting or scanning for prey. Watch without flash or disturbance, never chase a jumper across a wall, and do not infer aggression from a turn or a single hop.

Australian distribution

The current World Spider Catalog records Cosmophasis thalassina from Malaysia to Australia, while the Australian Faunal Directory accepts the Australian species name and lists older synonyms. This page retains a Queensland-only quick filter because the Australian field context and project inventory are northern and subtropical; it does not claim that every northern record has the same local extent or that a Queensland photograph proves the species. Lizard Island material and the Queensland Museum jumping-spider guide support warm tropical and subtropical habitat clues. Record a broad Queensland region and the plant or wall setting, never a precise address. Outside the expected context, or where a similar Cosmophasis species is plausible, use the genus-level result and seek expert confirmation.

What to do if you find one

Observe from a little distance and photograph the whole spider from above or slightly to the side, with the leaf, wall or garden setting included. Avoid flash at close range, blocking its escape route or placing hands behind it; jumping spiders are small and can disappear between surfaces. Wear closed shoes when working around garden beds and use care with stored pots, timber and foliage. If one is indoors, give it space and use a professional removal option if needed rather than trapping it for a photograph. Jumping spiders are not usually considered medically important, but wash any suspected bite and seek medical advice for marked or persistent symptoms, allergic signs or uncertainty. Call 000 for collapse, breathing difficulty or anaphylaxis rather than delaying first aid for identification.

Compare with similar spiders

Use body shape, web or retreat, location and behaviour together before settling on a likely match.

• Sparkling northern jumping spider — Sparkling northern jumping spider - Cosmophasis micarioides can share the northern metallic black-and-white look. Lizard Island guidance notes that C. thalassina male carapace bands stop short of the rim; a routine photo may not show that boundary.
• Green jumping spider — Green jumping spider - Mopsus mormon is larger and differently built, with a broader green body and a different route through foliage. Green colour alone does not choose between them.
• Garden jumping spider — Garden jumping spider - a small Opisthoncus may share walls, leaves and stop-start movement but lacks a reliable metallic Cosmophasis pattern in many photographs.
• Peacock spider — Peacock spider - Maratus males use a fan and display in a different salticid route. A bright iridescent patch is not evidence of a fan-bearing peacock spider.

Sources for this profile

These accessible authoritative sources support the identification and bite-safety context on this page.

• World Spider Catalog: Cosmophasis thalassina
• World Spider Catalog: Cosmophasis catalogue
• Australian Faunal Directory: Cosmophasis thalassina
• Atlas of Living Australia: Cosmophasis thalassina
• Lizard Island Field Guide: Cosmophasis thalassina
• Zenodo: Cosmophasis thalassina treatment
• Peckhamia 312.1: new synonymy for Cosmophasis thalassina
• Lucid Central: Cosmophasis factsheet
• Australian Museum: Jumping spiders
• Queensland Museum: New jumping-spider species
• Wikimedia Commons: exact Cosmophasis thalassina photograph
• healthdirect: Spider bites

Profile review

Published by Spider Identifier Australia. Last factual review: 13 August 2026.