blindness and area echo

Seems like blindness should not allow me to see the small crab. log snipet: <100%hp 81%m 100%mv 5018tnl (40.26%) (wilderness)> af You are affected by: Spell: 'detect magic' for 27 hours. Spell: 'detect invis' for 22 hours. Spell: 'water breathing' for 18 hours. Spell: 'slow' modifies dexterity by -3 for 2 hours. Spell: 'blindness' modifies hit roll by -4 for 1 hours. <100%hp 91%m 100%mv 5018tnl (40.26%) (wilderness)> Something decomposes. <100%hp 91%m 100%mv 5018tnl (40.26%) (wilderness)> Someone has arrived. <100%hp 100%m 100%mv 5018tnl (40.26%) (wilderness)> A small crab skitters out from underneath a nearby rock, kicking up dirt that clouds the water for a moment before settling again. <100%hp 100%m 100%mv 5018tnl (40.26%) (wilderness)> af You are affected by: Spell: 'detect magic' for 26 hours. Spell: 'detect invis' for 21 hours. Spell: 'water breathing' for 17 hours. Spell: 'slow' modifies dexterity by -3 for 1 hours. Spell: 'blindness' modifies hit roll by -4 for 0 hours. <100%hp 100%m 100%mv 5018tnl (40.26%) (wilderness)> You can see again. <100%hp 100%m 100%mv 5018tnl (40.26%) (wilderness)> You speed up again.