Care guide
Selenopid Crab Spider (Flattie)
Selenops sp.
An impossibly flat, wall-hugging ambush hunter that is one of the fastest spiders alive. Low-maintenance, but nearly impossible to catch once loose, so keep the lid secured.
Selenops sp.
Identity confidence: provisional. This is a genus, group, or trade name rather than a confirmed species. Treat it as the closest match we can stand behind, and use the more conservative end of any range.
Selenopid Crab Spider (Flattie): Advanced Care Guide
Keeper Snapshot: An impossibly flat, wall-hugging ambush hunter that is one of the fastest spiders alive. Low-maintenance, but nearly impossible to catch once loose, so keep the lid secured.
Group: Spiders & Other InvertsDifficulty: Spice 2: BeginnerSetup: Vertical wall/bark-crevice flattened hunterHandling: Not recommended (extremely fast)
Use This Guide Safely
- Confirm the exact animal. Match this guide to the species, locality, size, and life stage on your label. If the ID is uncertain, use the more conservative part of the range and ask before changing the setup.
- Change one thing at a time. Treat temperature and humidity as target zones, then watch posture, burrowing, drinking, feeding, and molt behavior before making another adjustment.
- Respect the handling boundary. If the guide says no handling, fast, defensive, or medically significant, plan transfers with catch cups, locked lids, and no bare hands. For serious bites, stings, or symptoms, seek emergency medical care.
Quick Snapshot
| Temperature | 72-82°F |
|---|---|
| Humidity | Low-Moderate ambient (45-60%) with strong cross ventilation; dry crevices, small dish |
| Setup Type | Vertical wall/bark-crevice flattened hunter |
| Substrate | Thin dry substrate plus vertical bark/rock surfaces |
| Feeding | 1/8-1/4" crickets/roach nymphs/flies (no larger than body length); weekly, offered at dusk |
| Care Difficulty | Spice 2: Beginner |
| Handling | Not recommended (extremely fast) |
Humidity zones: Very Low under 30% - Low 30-60% - Low-Moderate 40-70% - Moderate 60-80% - Moderate-High 70-85% - High 80%+ - Very High 90%+
Enclosure Format / Size Class
- small vertical bark/crevice setup for all life stages
Warnings First
- Extremely fast, among the fastest recorded spider strike/turn speeds
- Flattened body lets it squeeze through gaps most enclosures don't seal
- Harmless bite, but very difficult to recapture if it escapes
- Do not open the enclosure without a secure room or catch container ready
- A flattened crevice-dweller sits in a gap with zero passive airflow. The crevice is only as fresh as the enclosure around it, so vent low on two opposite walls.
Simple Care
- Give vertical bark or rough stone surfaces rather than floor space. This species hunts on walls, not the ground.
- Vents low on two opposite walls in fine bonded mesh: airflow past the crevices, with no gap a flattened body can exploit.
- Keep the enclosure lightly humid with good airflow; avoid standing water.
- If you offer water, use a shallow dish packed with grit rather than an open surface.
- Feed small appropriately sized prey weekly; this is not a heavy eater.
- Seal every seam and vent gap. Their flattened body is built to exploit small openings.
Advanced Keeper Notes
Enclosure & Microclimate
- Selenopids are dorsoventrally flattened specifically to live in narrow crevices under bark and rock. Vertical cork or rough-textured backgrounds matter far more than substrate depth.
- Keep humidity moderate with strong ventilation. This is a dry-crevice specialist, not a humidity-loving species.
- The crevice itself is the reason ventilation placement matters. A flattened spider pressed into a gap under bark gets no air movement of its own, so whatever the surrounding enclosure does is what the crevice does. Put vents low on two opposite walls so air crosses behind and around the bark rather than only passing over the lid, and the crevice stays dry between mistings.
- That does mean reconciling airflow with the escape problem, and the answer is fine bonded mesh with many small openings rather than a few larger ones. Same airflow, no gap a dorsoventrally flattened body can work through, and the mesh edges matter as much as the gauge on this species.
- On a dry-crevice specialist the ventilation and humidity trade favors air. Ambient at 45 to 60% is right and drifting lower is fine.
- Judge by touching the bark rather than by a gauge. Cork and stone faces should read dry, including behind them where you can reach. Anywhere that stays damp is where a problem will start.
- If you keep standing water rather than misting, use a shallow dish packed with grit so there is no open surface. Otherwise mist one wall lightly for drinking droplets and let it dry back fully.
Feeding, Growth & Maintenance
- Feeding: small crickets, roach nymphs, or flies no larger than the spider's body length, roughly 1/8-1/4in. Offer weekly in the evening; don't oversize prey given this species' light, flattened build.
- Growth: several molts to maturity in under a year for most Selenops species; lifespan roughly 1-2 years.
- Maintenance: remove uneaten prey within 24-48 hours, and stop feeding at the first signs of premolt (dulled color, reduced activity) until the new exoskeleton hardens, usually just a few days given the small size.
Possible Origin / Range
- Likely native range: Tropical and subtropical regions worldwide, including the southern and southwestern United States, on walls, bark, and rock crevices.
- Habitat translation: A vertical crevice-style setup with bark or rough stone, kept dry-leaning with strong airflow.
Advanced Keeper Details
- Their sideways leg posture and extreme flattening are built for wedging into cracks a fraction of their body height. Assume any unsealed gap is an escape route.
- Strike and turning speed are among the fastest measured in any terrestrial animal. Do not attempt to handle or free-catch this species.
- Species-level identification within Selenops is difficult without a specialist; this guide covers general care for US/import Selenops sp. in the trade.
Selenops sp.
Identity confidence: provisional. This is a genus, group, or trade name rather than a confirmed species. Treat it as the closest match we can stand behind, and use the more conservative end of any range.
Selenopid Crab Spider (Flattie)
Big Z's Quick Verdict: An impossibly flat, wall-hugging ambush hunter that is one of the fastest spiders alive. Low-maintenance, but nearly impossible to catch once loose, so keep the lid secured.
Group: Spiders & Other InvertsDifficulty: Spice 2: BeginnerSetup: Vertical wall/bark-crevice flattened hunterHandling: Not recommended (extremely fast)
Use This Guide Safely
- Confirm the exact animal. Match this guide to the species, locality, size, and life stage on your label. If the ID is uncertain, use the more conservative part of the range and ask before changing the setup.
- Change one thing at a time. Treat temperature and humidity as target zones, then watch posture, burrowing, drinking, feeding, and molt behavior before making another adjustment.
- Respect the handling boundary. If the guide says no handling, fast, defensive, or medically significant, plan transfers with catch cups, locked lids, and no bare hands. For serious bites, stings, or symptoms, seek emergency medical care.
Quick Care Snapshot
| Temp | 72-82°F |
|---|---|
| Humidity | Low-Moderate ambient (45-60%) with strong cross ventilation; dry crevices, small dish |
| Setup | Vertical wall/bark-crevice flattened hunter |
| Substrate | Thin dry substrate plus vertical bark/rock surfaces |
| Feeding | 1/8-1/4" crickets/roach nymphs/flies (no larger than body length); weekly, offered at dusk |
| Handling | Not recommended (extremely fast) |
Humidity zones: Very Low under 30% - Low 30-60% - Low-Moderate 40-70% - Moderate 60-80% - Moderate-High 70-85% - High 80%+ - Very High 90%+
Recommended Big Z's Setup
- Bark Buddy for a vertical crevice-style setup
Critical Notes
- Extremely fast, among the fastest recorded spider strike/turn speeds
- Flattened body lets it squeeze through gaps most enclosures don't seal
- Harmless bite, but very difficult to recapture if it escapes
- Do not open the enclosure without a secure room or catch container ready
- A flattened crevice-dweller sits in a gap with zero passive airflow. The crevice is only as fresh as the enclosure around it, so vent low on two opposite walls.
Care Basics
- Give vertical bark or rough stone surfaces rather than floor space. This species hunts on walls, not the ground.
- Vents low on two opposite walls in fine bonded mesh: airflow past the crevices, with no gap a flattened body can exploit.
- Keep the enclosure lightly humid with good airflow; avoid standing water.
- If you offer water, use a shallow dish packed with grit rather than an open surface.
- Feed small appropriately sized prey weekly; this is not a heavy eater.
- Seal every seam and vent gap. Their flattened body is built to exploit small openings.
Feeding, Growth & Maintenance
- Feeding: small crickets, roach nymphs, or flies no larger than the spider's body length, roughly 1/8-1/4in. Offer weekly in the evening; don't oversize prey given this species' light, flattened build.
- Growth: several molts to maturity in under a year for most Selenops species; lifespan roughly 1-2 years.
- Maintenance: remove uneaten prey within 24-48 hours, and stop feeding at the first signs of premolt (dulled color, reduced activity) until the new exoskeleton hardens, usually just a few days given the small size.
Current Big Z's catalog: Yes
Selenops sp.
Identity confidence: provisional. This is a genus, group, or trade name rather than a confirmed species. Treat it as the closest match we can stand behind, and use the more conservative end of any range.
Selenopid Crab Spider (Flattie): Advanced Care Guide
Keeper Snapshot: An impossibly flat, wall-hugging ambush hunter that is one of the fastest spiders alive. Low-maintenance, but nearly impossible to catch once loose, so keep the lid secured.
Group: Spiders & Other InvertsDifficulty: Spice 2: BeginnerSetup: Vertical wall/bark-crevice flattened hunterHandling: Not recommended (extremely fast)
Use This Guide Safely
- Confirm the exact animal. Match this guide to the species, locality, size, and life stage on your label. If the ID is uncertain, use the more conservative part of the range and ask before changing the setup.
- Change one thing at a time. Treat temperature and humidity as target zones, then watch posture, burrowing, drinking, feeding, and molt behavior before making another adjustment.
- Respect the handling boundary. If the guide says no handling, fast, defensive, or medically significant, plan transfers with catch cups, locked lids, and no bare hands. For serious bites, stings, or symptoms, seek emergency medical care.
Quick Snapshot
| Temperature | 72-82°F |
|---|---|
| Humidity | Low-Moderate ambient (45-60%) with strong cross ventilation; dry crevices, small dish |
| Setup Type | Vertical wall/bark-crevice flattened hunter |
| Substrate | Thin dry substrate plus vertical bark/rock surfaces |
| Feeding | 1/8-1/4" crickets/roach nymphs/flies (no larger than body length); weekly, offered at dusk |
| Care Difficulty | Spice 2: Beginner |
| Handling | Not recommended (extremely fast) |
Humidity zones: Very Low under 30% - Low 30-60% - Low-Moderate 40-70% - Moderate 60-80% - Moderate-High 70-85% - High 80%+ - Very High 90%+
Enclosure Format / Size Class
- small vertical bark/crevice setup for all life stages
Warnings First
- Extremely fast, among the fastest recorded spider strike/turn speeds
- Flattened body lets it squeeze through gaps most enclosures don't seal
- Harmless bite, but very difficult to recapture if it escapes
- Do not open the enclosure without a secure room or catch container ready
- A flattened crevice-dweller sits in a gap with zero passive airflow. The crevice is only as fresh as the enclosure around it, so vent low on two opposite walls.
Simple Care
- Give vertical bark or rough stone surfaces rather than floor space. This species hunts on walls, not the ground.
- Vents low on two opposite walls in fine bonded mesh: airflow past the crevices, with no gap a flattened body can exploit.
- Keep the enclosure lightly humid with good airflow; avoid standing water.
- If you offer water, use a shallow dish packed with grit rather than an open surface.
- Feed small appropriately sized prey weekly; this is not a heavy eater.
- Seal every seam and vent gap. Their flattened body is built to exploit small openings.
Advanced Keeper Notes
Enclosure & Microclimate
- Selenopids are dorsoventrally flattened specifically to live in narrow crevices under bark and rock. Vertical cork or rough-textured backgrounds matter far more than substrate depth.
- Keep humidity moderate with strong ventilation. This is a dry-crevice specialist, not a humidity-loving species.
- The crevice itself is the reason ventilation placement matters. A flattened spider pressed into a gap under bark gets no air movement of its own, so whatever the surrounding enclosure does is what the crevice does. Put vents low on two opposite walls so air crosses behind and around the bark rather than only passing over the lid, and the crevice stays dry between mistings.
- That does mean reconciling airflow with the escape problem, and the answer is fine bonded mesh with many small openings rather than a few larger ones. Same airflow, no gap a dorsoventrally flattened body can work through, and the mesh edges matter as much as the gauge on this species.
- On a dry-crevice specialist the ventilation and humidity trade favors air. Ambient at 45 to 60% is right and drifting lower is fine.
- Judge by touching the bark rather than by a gauge. Cork and stone faces should read dry, including behind them where you can reach. Anywhere that stays damp is where a problem will start.
- If you keep standing water rather than misting, use a shallow dish packed with grit so there is no open surface. Otherwise mist one wall lightly for drinking droplets and let it dry back fully.
Feeding, Growth & Maintenance
- Feeding: small crickets, roach nymphs, or flies no larger than the spider's body length, roughly 1/8-1/4in. Offer weekly in the evening; don't oversize prey given this species' light, flattened build.
- Growth: several molts to maturity in under a year for most Selenops species; lifespan roughly 1-2 years.
- Maintenance: remove uneaten prey within 24-48 hours, and stop feeding at the first signs of premolt (dulled color, reduced activity) until the new exoskeleton hardens, usually just a few days given the small size.
Possible Origin / Range
- Likely native range: Tropical and subtropical regions worldwide, including the southern and southwestern United States, on walls, bark, and rock crevices.
- Habitat translation: A vertical crevice-style setup with bark or rough stone, kept dry-leaning with strong airflow.
Advanced Keeper Details
- Their sideways leg posture and extreme flattening are built for wedging into cracks a fraction of their body height. Assume any unsealed gap is an escape route.
- Strike and turning speed are among the fastest measured in any terrestrial animal. Do not attempt to handle or free-catch this species.
- Species-level identification within Selenops is difficult without a specialist; this guide covers general care for US/import Selenops sp. in the trade.