Among the more unusual piscine species is the
South American Lungfish (Lepidosiren paradoxa).
This eel- like fish with large scales and thin ribbonlike
fins can gulp air in the manner of its ancestors that
swam in stagnant lakes 350 million years ago. There
are two other lungfish species, one in Africa and one
in Australia. The curious distribution of these three
species of ancient freshwater fish on three widely
separated continents is almost surely the result of plate
tectonics and the breakup of Gondwana.
Catfish (plate 10- 26) are abundant and diverse in
the Amazon and its tributaries. Some get to be very
large, but not all. Vandellia cirrhosa, one member of
a group of bizarre catfish collectively called candirus,
is potentially irksome. Slimmer than a pencil, this
tiny fish is normally a parasite of other fish, attaching
to gills. However, it allegedly has the disconcerting
habit of (presumably) mistakenly swimming into the
human urethral, vaginal, or anal opening, whereupon
it lodges itself with an array of sharp fin spines. Though
candirus are widely reputed to have this unfortunate
mistaken sense of direction, I have been unable to
locate any evidence other than anecdotal accounts of
attempted or actual invasion. Nonetheless, candirus do
have the potential to be truly dangerous, to say nothing
of painful, and it is worth being aware in areas where
these fish are known to occur.Coastal Mangroves: Saltwater
Forests that Protect Coast and
Enrich SeasMangrove forest, sometimes termed mangal,
lines tropical coasts, lagoons, and offshore islands
throughout the global tropics. The term mangrove is not
taxonomic but rather refers to a series of characteristics
that mangrove trees have in common. In other words,
the designation mangrove is based on physiological
adaptations, most specifically the collective ability of
mangrove trees to tolerate immersion in salty water
(plates 12- 64– 65). Mangroves are not diverse and
thus tend to form pure stands or stands of low species
richness. They often have aerial roots of some sort.
Many mangroves, though distinct from their nearest
terrestrial relatives at the species level, have fairly close
relatives on terra firme.
Mangrove forests form essential habitat for many
kinds of marine animals. Frigatebirds (Fregata spp.; seeplates 12- 68– 69) as well as many other species of birds
commonly nest among mangroves. Migrant birds
use mangroves as valuable wintering areas, because
mangrove forests are rich in arthropod food. Perhaps
most important, mangroves capture a great deal of
energy that supports a rich marine ecosystem and
contributes to the health of offshore marine ecosystems
such as coral reefs.
Mangrove leaves that drop decompose slowly, and
numerous invertebrates and microbial organisms use
them as a food source. As microbial communities
cover the decomposing mangrove leaf, the carbon-Plate 12- 64. The leaves of this Red Mangrove (Rhizophora
mangle) are thick and waxy, resistant to salt spray and water
loss. Note the seedling that will drop from the branch and
float, perhaps reaching a sandbar to colonize. Photo by
Dennis Paulson.Plate 12- 65. The prop roots of this Red Mangrove cluster help
protect inland vegetation and thus act to stabilize coastal
ecosystems, buffering them from hurricanes and other coastal
storms. Photo by Dennis Paulson.chapter 12 cruising the rivers to the sea 229