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Cephalopods, as a whole, are a particularly weird group
of animals. Looking into the strangely human eyes of an octopus or squid,
one is struck by the weight of what might have been, had vertebrates not
been so quick to grab the aquatic niches. On Spec, an entire world of might-have-beens,
the weight of this question approaches that of a sledgehammer blow. Spec's
land is home to giant dinosaurs, saved from destruction by happy coincidence,
and the oceans are, for the same reason, home to a very wide range of tentacled
mollusks.
Nautiluses
Like in Home-Earth, a few species of nautilus, distinguished by the simple
internal walls of their shells, their huge number of tentacles, their yolk-rich
eggs, and their protective hood or lid, have survived age after age in Spec. As
far as the young science of Specpalaeontology can tell, the Palaeocene and
Eocene
radiation of nautiloids observed in our timeline did not happen in Spec, but the
current result, a few species of p-Nautilus in and around the western
Pacific Ocean, seems to be identical.
Curlies, barrelfish, bulletfish, pizzafish, etc.
Probably the most famous fossil form, the shape of ancient organism recognized
by anyone in any place where such rocks occur, is the coiled ram's-horn shell
of an ammonoid. Extinct in Home-Earth, ammonites are still plentiful in Spec's
oceans; their larvae make up a considerable component of the plankton.
Aside from the ammonoids and nautiloids, all modern cephalopods belong to the
Coleoidea, most remarkable for their internalised shell. This
clade includes the Belemnoidea (which retain a well-developped internal shell)
and the Neocoleoidea (whose shells are reduced or absent).
Cleaner-squids, hitchhiker-squids, leechsquids, and baleen-squids
Belemnoids are a group of cephalopods superficially similar to squids. They
possess advanced eyes and nervous systems and an ink sac, and they bear suckers
and chitinous hooks on their tentacles, just like true squids. However,
belemnoids retain ten equal tentacles (rather than elongating and specialising
the fourth pair), and their nether regions, which,
in squids, are supported by a flimsy pen, contain a complex torpedo-shaped
structure similar to the shell of an ammonoid. This internal shell, the belemnite
structure, is not coiled, as in most ammonoids, but straight, composed of
a bullet-shaped, calcite rostrum, a chambered phragmocone, and a proostracum
which extends to protect the head. As in ammonoids and nautiloids it functions
primarily as a buoyancy organ.
In our home timeline, belemnoids went extinct at the end of the
Cretaceous, doomed by the same calamity that killed the dinosaurs and the ammonoids.
In Spec, these squid-like creatures of course survived and diversified somewhat in the
Eocene. The
Eocene-Oligocene
mass extinction destroyed much of this diversity. It is in the Eocene that the first baleen-squid
remains appear, however, and these early fossils show that baleen-squid are most
probably belemnites, so these quirky cephalopods have apparently not fared so poorly
after all. Today’s easily recognizable belemnoids exist in only a few specialized
niches. These are the conservative cleaner-squids, which are found mainly in the Caribbean
Reef, but may have a larger range, and the cosmopolitan hitchhiker-squids
and leechsquids,
which are found in equatorial oceans the world over. Modern cleaner-squids are distinguished from their Cretaceous ancestors
by several unique features. The rostrum (covered by the muscular mantle)
is short and conical, forming the tip of the rear end of the animal. The
phragmocone, which occupies the bulk of the cleaner-squid's hind portion,
carries a number of chambers and is used by the animal to regulate buoyancy
to sink or float. The proostracum, on the other hand, is reduced, forming
the base for a fleshy hood. Like true squids, cleaner-squids have two "fins",
flexible extensions of the mantle on either side of their bodies that allow
them to maneuver with great facility.
In some respects a cleaner-squid had certain
advantages when they came to occupy that niche that, in our timeline, is
occupied by the cleaner wrasse and various shrimps. As a small cephalopod, the cleaner-squid
was already the predators of small crustaceans, and was already capable of
the complex signaling that the modern cleaner squid uses to advertise their
services.
The banded cleaner squid (Utiliteuthis formosus) is a striking blue and black belemnoid, occupying the same
niche as cleaner shrimps and wrasses in Home-Earth. The species its uses hooked tentacles
to groom other animals – teleosts and sharks for the most part – free of
parasitic crustaceans. These cleaners live in small schools, never far
from the shelter of the reefs. The cleaner-squid's internal shell is thin
and light – the species is too quick and too useful to have many predators.
(fig. 1) Banded cleaner-squid, Utiliteuthis
formosus (Caribbean Reef)
(fig. 2) Left and center: Common hitchhiker, Remorateuthis denti
(cosmopolitan). Center: the suction plate
composed of the 10 fused tentacles. Right: Mantasquid hitchhiker, Remorateuthis
prefecti, attached
to a bumblebee
squid, Papilioteuthoides bombus (tropical oceans).
Hitchhiker-squids (Remorateuthis) have almost completely lost their
internal shells. They use their suction plate which consists of the fused,
shortened tentacles to grab on to large fish, marine
reptilians or baleen-squids for a free
ride. Several species have been described which show a certain preference for
certain hosts, for example the common hitchhiker (R. denti) which will
stick to anything but is most commonly found on turtles,
the mantasquid hitchhiker (R. prefecti) which is usually found attached
to mantasquid, the great hitchhiker (R. adamsi) which prefers
giant
baleen-squids, and the long-armed, beautifully patterned starry sucker (R.
beeblebroxi) of which so far only two specimens have been found, both
clinging to Pacific
wingheads.
The seas of Spec have a lot of nasty surprises in store for a would-be scuba diver. While large carnivores such as
mosarks and penguins of death are among the most feared of marine organisms, some of the most most vile creatures
are so small or inconspicuous you won't even think of them as threatening until it's too late. The leechsquid fits
neatly in the latter category.
 The leechsquids
(Nosferateuthis) are curious tiny cousins of the hitchhiker-squids, which
have gone from mere freeriders to downright parasitic bloodsuckers. The mouths
of the these 5- to 13-cm-long cephalopods are surrounded with stubby
tentacles with suction cups and one curved claw-like hook each. The leechsquid
uses these clasps to latch onto its victim before it proceeds to bite through
the skin with its sharp chitinous beak. When the leechsquid pierces the skin
it injects an anaesthetic agent into the host's tissue and bloodstream. Thanks
to this chemical, the leechsquid can often feed without the host even noticing
its presence. A stationary leechsquid is also very hard to see, as it can
mimic the colour and texture of the surface it is resting on.
(fig. 2) _ leechsquid, Nosferateuthis haemophilus (equatorial oceans)
[needs two more tentacles]
BALAENATEUTHIA
Baleen-squid
The rich plankton of Spec's cold waters is eaten by all manner of animals,
such as ammonites and sharks, but the biggest and most impressive plankton
eaters are the baleen-squids, belemnites with highly modified arms, fins and
body sizes.
Squids, octopuses, and vampyromorphs
Due to the continued presence of ammonites, the familiar true squids and
octopuses are less diverse in Spec than in our home timeline. They are, however,
important members of marine ecosystems in both worlds, especially in the deep
sea where the gas-filled shells of nautiloids and ammonoids would be crushed by
the water pressure. In short, apart from Spec's lack of cuttlefishes
(Sepioidea), its
dibranchiates are very similar to those of Home-Earth, most species being
indistinguishable between the two timelines. Some ecologists speculate that Spec
might, for theoretic reasons, have a somewhat greater diversity of
vampyromorphs, but this is hard to test, badly researched as these animals are
in both universes!
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