July 23. Philippine Marine Biodiversity - Definitives
Amstar Company, Inc. Perf. 13.5
of 100 (10 x 10)
15p - Bowmouth Guitarfish - Singles
Chambered Nautilus - Singles (3,270,000)
L. Mercado (15p); Lino B. Jamisola (30p)
Graphic Artist: Earvin L. Ayes
Design Coordinators: Victorino Z. Serevo; Elenita D.L.
Source: Coral Reef Animals of the Indo-Pacific by Dr. Terence
First Day Covers: Manila
Guitarfish (Rhina Ancylostoma).
The bowmouth guitarfish, mud skate, or shark
ray (Rhina ancylostoma is found widely in the tropical coastal
waters of the Indo-Pacific region, at depths of up to 90 m (300 ft).
Highly distinctive in appearance, the bowmouth guitarfish has a
wide, thick body with a blunt snout and large, shark-like dorsal and
tail fins. The line of its mouth is strongly undulating, and there
are multiple thorny ridges over its head and back. It has dorsal
color pattern of many white spots over a bluish gray to brown
background, with a pair of prominent markings over the pectoral
fins. This large species can grow to 2.7 m (8.9 ft) long and 135 kg
(300 lb). Strong-swimming and demersal in nature, the bowmouth
guitarfish prefers sandy or muddy flats and areas adjacent to reefs,
where it hunts for crustaceans, molluscs, and bony fishes. The
International Union for Conservation of Nature (IUCN) has assessed
this species as Vulnerable; its sizable pectoral fins are greatly
valued as food and it is widely caught by artisanal and commercial
Chambered Nautilus (Nautilus pompilius).
The best-known species of nautilus. The shell, when cut away reveals
a lining of lustrous nacre and displays a nearly perfect equiangular
spiral. The shell exhibits counter shading, being light on the
bottom and dark on top. This is to help avoid predators because when
seen from above, it blends in with the darkness of the sea, and when
seen from below, it blends in with the light coming from above. The
animal has more primitive eyes than some other cephalopods; the eye
has no lens and thus is comparable to a pinhole camera. The animal
has about 90 tentacles with no suckers, which is also different from
other cephalopods. This nocturnal animal has a pair of rhinophores,
which detect chemicals, and uses olfaction and chemotaxis in order
to find its food.
Articles by Dr. Ngo Tiong Tak