Page 316 - (DK) Ocean - The Definitive Visual Guide

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PHYLUM HEMICHORDATA PHYLUM SIPUNCULA
Acorn Worm Peanut Worm

Glossobalanus sarniensis Golfingia vulgaris
SIZE Not recorded LENGTH Up to 8 in (20 cm)
DEPTH Shallow water DEPTH 0–6,560 ft (0–2,000 m)
HABITAT Soft sediments HABITAT Muddy sand and gravel
DISTRIBUTION Coastal temperate waters of DISTRIBUTION Northeastern Atlantic and eastern
northeastern Atlantic Mediterranean; possibly Indo-Pacific, Southern Ocean
The soft, slimy body of this wormlike The peanut worm is shaped like a
animal is divided into three regions. At half-inflated sausage balloon. Its body
the front end is a pointed proboscis, is stout and has a long, thin region at
separated from the long, thin trunk by the front called the introvert, which
a tubelike collar. It lives in a U-shaped can be stretched right out or withdrawn
burrow and feeds by trapping small completely inside the body. The
organisms in sticky mucus and eating animal has a crown of short tentacles
sediment. The sexes are separate, and around the mouth at the end of the
reproduction can be either asexual, by introvert. It lives buried in sediment,
fragmentation or budding, or sexual. which it eats as it burrows and digests
Some biologists group acorn worms any organic matter.
with pterobranch worms (see below)
in one phylum, the Hemichordata. plump extended
body
introvert
Unusually for invertebrates, they have
some vertebrate characteristics, which
include a nerve cord that runs
along the back.

which encrusts rock surfaces or can
PHYLUM PHORONIDA PHYLUM HEMICHORDATA
bore into shells or limestone rock
Horseshoe Worm so that only the top part of the tube Pterobranch Worm
shows. The end of the wormlike body
is thickened and anchors the animal in
Phoronis hippocrepia Rhabdopleura compacta
1
LENGTH Up to 4 in (10 cm) its tube. The feeding head with its LENGTH Up to / 2 in (5 mm)
horseshoe of delicate ciliated tentacles
DEPTH 0–165 ft (0–50 m) DEPTH Not recorded
is extended to catch tiny planktonic
HABITAT Rocks and empty shells HABITAT Attached to sessile animals
animals while the body remains
DISTRIBUTION Shallow coastal waters of Atlantic hidden in the tube. The feeding head is DISTRIBUTION Cold waters of northern hemisphere
Ocean, northeastern and western Pacific
called a lophophore and is found in all
members of the phylum. Horseshoe Like the acorn worms to which they
Horseshoe worms are easily overlooked worms brood their egg masses within are related (above, left), pterobranch
but they sometimes cover large areas of the lophophore, and larvae are worms live in a thin tube and their
rock with their narrow, membranous continually released to drift and bodies are divided into a proboscis,
tubes. The animal lives inside its tube, develop in the water. collar, and trunk. They also have a pair
of arms covered in tentacles arising
from the collar region. The tubes of
It is hard to see which end is which on many individuals are connected
PHYLUM NEMATODA
a roundworm, as both ends of its thin together with strands of soft tissue that
Roundworm body are pointed. The body is round join the trunks of the animals, enabling
in cross-section and has longitudinal them to form a colony.
Dolicholaimus marioni muscles but no circular ones. This
1
LENGTH Up to / 2 in (5 mm ) results in a characteristic way of moving
in which the body is thrashed in a The stout, cylindrical body of this
DEPTH Intertidal PHYLUM CEPHALORHYNCHA
single plane forming C- or S-shapes animal is divided into a short barrel-
HABITAT Among algae in rock pools
in the process. This is a marine species, Priapula Worm shaped proboscis at the head end, a
DISTRIBUTION Shores of the northeastern but roundworms also occur in vast longer trunk region, and a tail that
Atlantic
numbers in the soil and fresh water. Priapulus caudatus consists of small bladders attached to
LENGTH Up to 4 in (10 cm) a hollow stalk. The proboscis can be
withdrawn into the trunk. The mouth
DEPTH Not recorded
PHYLUM ECHIURA HABITAT Buried in sediment on the end of the proboscis is edged
with spines, which help the animal to
Spoonworm DISTRIBUTION Cold waters of north Atlantic and seize other small marine
Arctic Ocean
worms for food.
Bonellia viridis
LENGTH Up to 6 in (15 cm)
DEPTH 3 –330 ft (1–100 m)
HABITAT Muddy rocks
DISTRIBUTION Coastal temperate waters of is forked, and usually this is all that can
OCEAN LIFE Female spoonworms have a proboscis of sticky mucus, and the food is
northeastern Atlantic and Mediterranean
be seen of the worm. The proboscis
collects food particles with the help
that stretches out like an elastic band
moved along the proboscis and into
the mouth by the whipping
and can reach at least 3 ft (1 m) away
in search of food. The worm’s green,
movements of hairlike cilia. Male
pear-shaped trunk remains hidden
spoonworms are tiny and parasitic
between rocks, safe from predators.
on the females, their only function
In this species, the tip of the proboscis
being to fertilize the female’s eggs.