Where are venomous spines found on venomous fishes?
1 Anterior dorsal fin
2 Posterior dorsal fin
3 Caudal fin
4 Gill cover (operculum)
5 Pectoral fins (paired)
6 Pelvic fins (paired)
7 Anal fin
Surgeonfishes have erectable "blades" on each side of the tail base
Venom apparatus in various venomous fishes
a Tail spine of a stingray. On the ventral side there are 2 venom glands arranged in pairs. The spine is serrated and can cause deep wounds.
b Dorsal spine of a lionfish (Pterois sp.). There is a narrow venom gland on both sides of the slender spine. The spine and glands are surrounded by a fine integument.
c Dorsal spine of a stonefish (Synanceia sp.). A massive bony ray with a large venom gland on both sides that is surrounded by a sturdy integument.
1 Venom gland
2 Integument (enveloping sheath)
3 Calcified cartilaginous spine (a) or bony spine (b and c)
Morphological features of the of the most important culprits:
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-Cartilaginous fishes (Chondrichthyes) with a pair of five gill slits on the underside -Body flattened dorsoventrally, with broad, flat pectoral fins on each side -Span of the wing-like pectoral fins can reach up to more than 2 m in some stingrays -Long, whip-like tail that is clearly distinct from the body -On the top of the tail, close to its base or medially, there are one to several flat venomous spines, serrated on the sides and surrounded by an integumentary sheath. The venom glands are located underneath the spine, along two grooves running lengthwise (see Fig. 4.20a.). |
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-Robust body with large head, sometimes with spines on the head -Body size in most species between 10-50 cm -Often possess camouflage colouring, sometimes enhanced by loose flaps of skin -On each side of the head: bony plate that extends from the eye over the gill cover -Venomous species possess 12–15 venomous spines in the anterior dorsal fin, 1 in each of the pelvic fins and 3 in the anal fin.
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-Body length up to 40 cm -In shallow waters conspicuous warning colouring in shades red with contrasting white stripes; in deeper waters the red turns into shades of of brown which acts more as camouflage against the reef walls -Long, thin fin rays surround the whole body like a shield -Venomous spines on the dorsal fin (13), the pelvic fins (the front 2) and the anal fin (the front 3). |
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-Body length up to 40 cm -Compact, compressed body with a high back. -Erosa spp. is similarly compact and stout as Synanceia -Leptosynanceia, Pseudosynaceia and Trachycephalus have a more elongated form -Warty, tough and scaleless skin with loose flaps and algae growing on it -Perfectly camouflaged against the surrounding substrate -Mouth and eyes directed upwards; the eyes may even protrude above the outline of the head -Venomous spines: the 13 most anterior dorsal spines, 3 rays on the anal fin and 2 on the ventral fin |
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-Body elongated -Length up to 50 cm -Eyes and mouth directed upwards, body tapered toward the rear - 5–8 venomous rays in the anterior dorsal fin, as well as 1 venomous spine on each of the gill covers |